CORM-2 inhibits TXNIP/NLRP3 inflammasome pathway in LPS-induced acute lung injury

CORM-3 Inhibits the Inflammatory Response of Human Periodontal Ligament Fibroblasts Stimulated by LPS and High Glucose

Introduction

Diabetes has been recognized as an independent risk factor for periodontitis. Increasing evidences indicate that hyperglycemia aggravates inflammatory response of human periodontal ligament cells (hPDLCs). Carbon monoxide-releasing molecule-3 (CORM-3) is a water-soluble compound that can release carbon monoxide (CO) in a controllable manner. CORM-3 has been shown the anti-inflammatory effect in different cell lineages.

Methods

We stimulated periodontal ligament cells with LPS and high glucose. The expression of inflammatory cytokine was detected by ELISA. RT-qPCR, Western blot and immunofluorescence were used to detect the expression of TLR2, TLR4, RAGE and the activation of NF-κB pathway. We performed silencing and overexpression treatment of RAGE targeting the role of RAGE. We performed the immunostaining of paraffin sections of the periodontitis model in diabetes rats.

Results

The results showed that CORM-3 significantly inhibited the expression of inflammatory cytokine in hPDLCs stimulated with LPS and high glucose. CORM-3 also inhibited LPS and high glucose-induced expression of RAGE/NF-κB pathway and TLR2/TLR4/NF-κB pathway. Silence of RAGE resulted in significantly decreased expression of proteins above. Overexpression of RAGE significantly enhanced the expression of these factors. CORM-3 abrogated the effect of RAGE partially. In animal model, CORM-3 suppressed the inflammatory response of periodontal tissues in experimental periodontitis of diabetic rats.

Discussion

Our research proved CORM-3 reduced the inflammatory response via RAGE/NF-κB pathway and TLR2/TLR4/NF-κB pathway in the process of high glucose exacerbated periodontitis. These findings demonstrated the role of RAGE in the process of high glucose exacerbated periodontitis and suggested that CORM3 be a potential therapeutic strategy for the treatment of diabetes patients with periodontitis.

The Mechanism of Pyroptosis and Its Application Prospect in Diabetic Wound Healing

Pyroptosis defines a form of pro-inflammatory-dependent programmed cell death triggered by gasdermin proteins, which creates cytoplasmic pores and promotes the activation and accumulation of immune cells by releasing several pro-inflammatory mediators and immunogenic substances upon cell rupture. Pyroptosis comprises canonical (mediated by Caspase-1) and non-canonical (mediated by Caspase-4/5/11) molecular signaling pathways. Numerous studies have explored the contributory roles of inflammasome and pyroptosis in the progression of multiple pathological conditions such as tumors, nerve injury, inflammatory diseases and metabolic disorders. Accumulating evidence indicates that the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome results in the activation of pyroptosis and inflammation. Current evidence suggests that pyroptosis-dependent cell death plays a progressive role in the development of diabetic complications including diabetic wound healing (DWH) and diabetic foot ulcers (DFUs). This review presents a brief overview of the molecular mechanisms underlying pyroptosis and addresses the current research on pyroptosis-dependent signaling pathways in the context of DWH. In this review, we also present some prospective therapeutic compounds/agents that can target pyroptotic signaling pathways, which may serve as new strategies for the effective treatment and management of diabetic wounds.

Hypermethylation of PPARG-encoding gene promoter mediates fine particulate matter-induced pulmonary fibrosis by regulating the HMGB1/NLRP3 axis

The inflammatory response induced by fine particulate matter (PM2.5), a common class of air pollutants, is an important trigger for the development of pulmonary fibrosis. However, the specific mechanisms responsible for this phenomenon are yet to be fully understood. To investigate the mechanisms behind the onset and progression of lung fibrosis owing to PM2.5 exposure, both rats and human bronchial epithelial cells were subjected to varying concentrations of PM2.5. The involvement of the PPARG/HMGB1/NLRP3 signaling pathway in developing lung fibrosis caused by PM2.5 was validated through the utilization of a PPARG agonist (rosiglitazone), a PPARG inhibitor (GW9662), and an HMGB1 inhibitor (glycyrrhizin). These outcomes highlighted the downregulation of PPARG expression and activation of the HMGB1/NLRP3 signaling pathway triggered by PM2.5, thereby eliciting inflammatory responses and promoting pulmonary fibrosis. Additionally, PM2.5 exposure-induced DNA hypermethylation of PPARG-encoding gene promoter downregulated PPARG expression. Moreover, the DNA methyltransferase inhibitor 5-azacytidine mitigated the hypermethylation of the PPARG-encoding gene promoter triggered by PM2.5. In conclusion, the HMGB1/NLRP3 signaling pathway was activated in pulmonary fibrosis triggered by PM2.5 through the hypermethylation of the PPARG-encoding gene promoter.

Role of Gasotransmitters in Inflammatory Edema

Significance: Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are, to date, the identified members of the gasotransmitter family, which consists of gaseous signaling molecules that play central roles in the regulation of a wide variety of physiological and pathophysiological processes, including inflammatory edema. Recent Advances: Recent studies show the potential anti-inflammatory and antiedematogenic effects of NO-, CO-, and H2S-donors in vivo. In general, it has been observed that the therapeutical effects of NO-donors are more relevant when administered at low doses at the onset of the inflammatory process. Regarding CO-donors, their antiedematogenic effects are mainly associated with inhibition of proinflammatory mediators (such as inducible NO synthase [iNOS]-derived NO), and the observed protective effects of H2S-donors seem to be mediated by reducing some proinflammatory enzyme activities. Critical Issues: The most recent investigations focus on the interactions among the gasotransmitters under different pathophysiological conditions. However, the biochemical/pharmacological nature of these interactions is neither general nor fully understood, although specifically dependent on the site where the inflammatory edema occurs. Future Directions: Considering the nature of the involved mechanisms, a deeper knowledge of the interactions among the gasotransmitters is mandatory. In addition, the development of new pharmacological tools, either donors or synthesis inhibitors of the three gasotransmitters, will certainly aid the basic investigations and open new strategies for the therapeutic treatment of inflammatory edema. Antioxid. Redox Signal. 40, 272-291.

S14G-humanin alleviates acute lung injury by inhibiting the activation of NF-κB

Acute lung injury (ALI) is characterized by severely damaged alveoli and blood vessels, seriously affecting the health of patients and causing a high mortality rate. The pathogenesis of ALI is complex, with inflammatory reactions and oxidative stress (OS) mainly involved. S14G humanin (HNG) is derived from humanin (HN), which is claimed with promising anti-inflammatory functions. Herein, the protective influence of HNG on ALI will be explored in a mouse model. The ALI model was established in mice via intratracheal instillation of 3 mg/kg LPS, followed by an intraperitoneal injection of 3 and 6 mg/kg HNG, respectively. Thicker alveolar walls, aggravated neutrophil infiltration, and increased wet weight/dry weight (W/D) ratio were observed in ALI mice, accompanied by an aggravated apoptotic state, all of which were notably alleviated by HNG. Furthermore, increased number of total cells and neutrophils in bronchoalveolar lavage fluid (BALF), elevated secretion of inflammatory cytokines, enhanced reactive oxygen species (ROS) and Malondialdehyde (MDA) levels, and declined superoxide dismutase-2 (SOD2) levels were observed in ALI mice, which were markedly ameliorated by HNG. Moreover, the upregulated levels of NOD-like receptor family pyrin domain containing 3 (NLRP3), caspase-1, and caspases cleave gasdermin D N/caspases cleave gasdermin D FL (GSDMD N/GSDMD FL) in ALI mice were signally repressed by HNG. Lastly, the upregulation of Toll-like receptor 4 (TLR4) and p-p65/p65, and downregulation of IκB-α observed in ALI mice were sharply reversed by HNG. Collectively, HNG alleviated the ALI in mice by inhibiting the activation of nuclear factor kappa B (NF-κB) signaling.

Homer1 Protects against Retinal Ganglion Cell Pyroptosis by Inhibiting Endoplasmic Reticulum Stress-Associated TXNIP/NLRP3 Inflammasome Activation after Middle Cerebral Artery Occlusion-Induced Retinal Ischemia

Retinal ischemia, after cerebral ischemia, is an easily overlooked pathophysiological problem in which inflammation is considered to play an important role. Pyroptosis is a kind of cell death pattern accompanied by inflammation. Homer scaffold protein 1 (Homer1) has anti-inflammation properties and protects against ischemic injury. However, little is known about pyroptosis following middle cerebral artery occlusion (MCAO)-induced retinal ischemia and the regulatory mechanisms involved by Homer1 for the development of pyroptosis. In the present study, retinal ischemic injury was induced in mice by permanent MCAO in vivo, and retinal ganglion cells (RGCs) were subjected to Oxygen and Glucose Deprivation (OGD) to establish an in vitro model. It was shown that TXNIP/NLRP3-mediated pyroptosis was located predominantly in RGCs, which gradually increased after retinal ischemia and peaked at 24 h after retinal ischemia. Interestingly, the RGCs pyroptosis occurred not only in the cell body but also in the axon. Notably, the occurrence of pyroptosis coincided with the change of Homer1 expression in the retina after retinal ischemia and Homer1 also co-localized with RGCs. It was demonstrated that overexpression of Homer1 not only alleviated RGCs pyroptosis and inhibited the release of pro-inflammatory factors but also led to the increase in phosphorylation of AMPK, inhibition of ER stress, and preservation of visual function after retinal ischemia. In conclusion, it was suggested that Homer1 may protect against MCAO-induced retinal ischemia and RGCs pyroptosis by inhibiting endoplasmic reticulum stress-associated TXNIP/NLRP3 inflammasome activation after MCAO-induced retinal ischemia.

ANGPTL2 aggravates LPS-induced septic cardiomyopathy via NLRP3-mediated inflammasome in a DUSP1-dependent pathway

Angiopoietin-like protein 2 (ANGPTL2) was implicated in various cardiovascular diseases; however, its role in lipopolysaccharide (LPS)-related septic cardiomyopathy remains unclear. Herein, mice were exposed to LPS to generate septic cardiomyopathy, and adeno-associated viral vector was employed to overexpress ANGPTL2 in the myocardium. Besides, mice were treated with adenoviral vector to knock down ANGPTL2 in hearts. ANGPTL2 expressions in hearts and cardiomyocytes were upregulated by LPS challenge. ANGPTL2 overexpression aggravated, while ANGPTL2 silence ameliorated LPS-associated cardiac impairment and inflammation. Mechanically, we found that ANGPTL2 activated NLRP3 inflammasome via suppressing DUSP1 signaling, and NLRP3 knockdown abrogated the detrimental role of ANGPTL2 in aggravating LPS-induced cardiac inflammation. Furthermore, DUSP1 overexpression significantly inhibited ANGPTL2-mediated NLRP3 activation, and subsequently improved LPS-related cardiac dysfunction. In summary, ANGPTL2 exacerbated septic cardiomyopathy via activating NLRP3-mediated inflammation in a DUSP1-dependent manner, and our study uncovered a promising therapeutic target in preventing septic cardiomyopathy.

Crucial role of carbon monoxide as a regulator of diarrhea caused by cholera toxin: Evidence of direct interaction with toxin

The present study evaluated the role of heme oxygenase 1 (HO-1)/carbon monoxide (CO) pathway in the cholera toxin-induced diarrhea and its possible action mechanism. The pharmacological modulation with CORM-2 (a CO donor) or Hemin (a HO-1 inducer) decreased the intestinal fluid secretion and Cl- efflux, altered by cholera toxin. In contrast, ZnPP (a HO-1 inhibitor) reversed the antisecretory effect of Hemin and potentiated cholera toxin-induced intestinal secretion. Moreover, CORM-2 also prevented the alteration of intestinal epithelial architecture and local vascular permeability promoted by cholera toxin. The intestinal absorption was not altered by any of the pharmacological modulators. Cholera toxin inoculation also increased HO-1 immunoreactivity and bilirubin levels, a possible protective physiological response. Finally, using fluorometric technique, ELISA assay and molecular docking simulations, we show evidence that CO directly interacts with cholera toxin, forming a complex that affects its binding to GM1 receptor, which help explain the antisecretory effect. Thus, CO is an essential molecule for protection against choleric diarrhea and suggests its use as a possible therapeutic tool.

Inducible nitric oxide synthase activity mediates TNF-α-induced endothelial cell dysfunction

Inducible nitric oxide synthase (iNOS) and vascular endothelial dysfunction have been implicated in the development and progression of atherosclerosis. This study aimed to elucidate the role of iNOS in vascular endothelial dysfunction. Ultrahigh performance liquid chromatography-quadrupole time-of-flight mass spectrometry combined with multivariate data analysis was used to characterize the metabolic changes in human umbilical vein endothelial cells (HUVECs) in response to different treatment conditions. In addition, molecular biology techniques were employed to explain the molecular mechanisms underlying the role of iNOS in vascular endothelial dysfunction. Tumor necrosis factor-α (TNF-α) enhances the expression of iNOS, TXNIP, and the level of reactive oxygen species (ROS) facilitates the entry of nuclear factor-κB (NF-κB) into the nucleus and promotes injury in HUVECs. iNOS deficiency reversed the TNF-α-mediated pathological changes in HUVECs. Moreover, TNF-α increased the expression of tumor necrosis factor receptor-2 (TNFR-2) and the levels of p-IκBα and IL-6 proteins and CD31, ICAM-1, and VCAM-1 protein expression, which was significantly reduced in HUVECs with iNOS deficiency. In addition, treating HUVECs in the absence or presence of TNF-α or iNOS, respectively, enabled the identification of putative endogenous biomarkers associated with endothelial dysfunction. These biomarkers were involved in critical metabolic pathways, including glycosylphosphatidylinositol-anchor biosynthesis, amino acid metabolism, sphingolipid metabolism, and fatty acid metabolism. iNOS deficiency during vascular endothelial dysfunction may affect the expression of TNFR-2, vascular adhesion factors, and the level of ROS via cellular metabolic changes, thereby attenuating vascular endothelial dysfunction.NEW & NOTEWORTHY Inducible nitric oxide synthase (iNOS) deficiency during vascular endothelial dysfunction may affect the expression of tumor necrosis factor receptor-2 and vascular adhesion factors via cellular metabolic changes, thereby attenuating vascular endothelial dysfunction.

Evaluation of the Involvement of Heme Oxygenase-1 Expression in Discoid Lupus Erythematosus Lesions

Discoid lupus erythematosus (DLE) is a chronic autoimmune disease that primarily affects the skin, causing red, scaly patches that may be disfiguring and can cause permanent scarring. This study aimed to investigate the potential clinical and therapeutic applications of heme oxygenase-1 (HMOX1) in the context of DLE. Immunohistochemical staining and bioinformatics analysis were performed on skin biopsy samples from DLE patients to examine the levels of HMOX1 and to correlate with markers of inflammation. Our study revealed a negative correlation between HMOX1 levels and the inflammatory status of DLE lesions, as well as an inverse correlation between HMOX1 levels and the infiltration of M1 macrophages and activated mastocytes. These findings suggest that HMOX1 plays a crucial role in the regulation of inflammation in DLE and could be a potential therapeutic target and biomarker for DLE.

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.

Heme oxygenase-1 ameliorates endotoxin-induced acute lung injury by modulating macrophage polarization via inhibiting TXNIP/NLRP3 inflammasome activation

Acute lung injury (ALI) remains a global public health issue without specific and effective treatment options available in the clinic. Alveolar macrophage polarization is involved in the initiation, development and progression of ALI; however, the underlying mechanism remains poorly understood. Heme oxygenase-1 (HO-1) acts as an antioxidant in pulmonary inflammation and has been demonstrated to be linked with the severity and prognosis of ALI. In this study, the therapeutic effects of HO-1 were examined, along with the mechanisms involved, mainly focusing on alveolar macrophage polarization. HO-1 depletion induced higher iNOS and CD86 (M1 phenotype) expression but was significantly decreased in Arg-1 and CD206 (M2 phenotype) expression in BALF alveolar macrophages after equivalent LPS stimulation. We also found that HO-1 deletion distinctly accelerated the expression of inflammasome-associated components NLRP3, ASC and caspase-1 in vivo and in vivo and in vitro. Moreover, on the basis of LPS for MH-S cells, levels of TXNIP, NLRP3, ASC and caspase-1 were increased and HO-1 depletion exacerbated these changes, whereas double depletion of HO-1 and TXNIP partially mitigated these elevations. Also, HO-1 knockdown induced more M1 phenotype and less M2 phenotype compared with LPS alone, whereas double silence of HO-1 and TXNIP partially changed the polarization state. Taken together, we demonstrated that HO-1 could modulate macrophage polarization via TXNIP/NLRP3 signaling pathway, which could be a potential therapeutic target for ALI treatment.

Ceramide induces pyroptosis through TXNIP/NLRP3/GSDMD pathway in HUVECs

Background

Pyroptosis of endothelial cells is a new cause of endothelial dysfunction in multiple diseases. Ceramide acts as a potential bioactive mediator of inflammation and increases vascular endothelial permeability in many diseases, whether it can aggravate vascular endothelial injury by inducing cell pyroptosis remains unknown. This study was established to explore the effects of C8-ceramide (C8-Cer) on human umbilical vein vascular endothelial cells (HUVECs) and its possible underlying mechanism.

Methods

HUVECs were exposed to various concentrations of C8-Cer for 12 h, 24 h, 48 h. The cell survival rate was measured using the cell counting kit-8 assay. Western blotting and Real-time polymerase chain reaction (RT-PCR) were used to detect the pyroptosis-releated protein and mRNA expressions, respectively. Caspase-1 activity assay was used to detect caspase-1 activity. Hoechst 33342/propidium iodide double staining and flow cytometry were adopted to measure positive staining of cells. Lactate dehydrogenase release assay and enzyme-linked immunosorbent assay were adopted to measure leakage of cellular contents. FITC method was used to detect the permeability of endothelial cells. ROS fluorescence intensity were detected by flow cytometry.

Results

The viability of HUVECs decreased gradually with the increase in ceramide concentration and time. Ceramide upregulated the expression of thioredoxin interacting protein (TXNIP), NLRP3, GSDMD, GSDMD-NT, caspase-1 and Casp1 p20 at the protein and mRNA level in a dose-dependent manner. It also enhanced the PI uptake in HUVECs and upregulated caspase-1 activity. Moreover, it promoted the release of lactate dehydrogenase, interleukin-1β, and interleukin-18. Meanwhile, we found that ceramide led to increased vascular permeability. The inhibitor of NLRP3 inflammasome assembly, MCC950, was able to disrupt the aforementioned positive loop, thus alleviating vascular endothelial cell damage. Interestingly, inhibition of TXNIP either chemically using verapamil or genetically using small interfering RNA (siRNA) can effectively inhibit ceramide-induced pyroptosis and improved cell permeability. In addition, ceramide stimulated reactive oxygen species (ROS) generation. The pretreatment of antioxidant N-acetylcysteine (NAC), ROS scavenger, blocked the expression of pyroptosis markers induced by C8-cer in HUVECs.

Conclusion

The current study demonstrated that C8-Cer could aggravate vascular endothelial cell damage and increased cell permeability by inducing cell pyroptosis. The results documented that the ROS-dependent TXNIP/NLRP3/GSDMD signalling pathway plays an essential role in the ceramide-induced pyroptosis in HUVECs.

Melatonin alleviates lead-induced intestinal epithelial cell pyroptosis in the common carps (Cyprinus carpio) via miR-17-5p/TXNIP axis

Lead (Pb) has been concerned as one of the most severe hazardous contaminants, because it can cause pyroptosis in multiple tissues of mammals and birds. Melatonin (Mel) has attracted much interest for its role in governing intestinal injury via microRNAs (miRNAs). To explore the effect of Mel on Pb exposure-induced intestinal epithelial cell pyroptosis in common carps by regulating miR-17-5p/TXNIP axis, the Pb exposure and Pb-Mel treated models were constructed in vivo. The results elucidated that the suppressed expression of miR-17-5p and intensified level of TXNIP were primarily detected in Pb-exposed gut tissues, and both abolished with Mel addition, along with downregulated Pb-mediated elevated expression of NLRP3, CASP1, IL1β and GSDMD. Additionally, the targeting relationship between miR-17-5p and TXNIP were demonstrated by dual-luciferase reporter assay, and on this basis, miR-17-5p NC, mimic and inhibitor cell models were established. Thereby, Thereby, the expression of TXNIP in the miR-17-5p mimic groups was significant lower in the Pb-exposure but still elevated than the Control group, and the expression of NLRP3 and NLRP3-dependent pyrotposis-related genes performed consistent alterations. Noticeably, the expression of TXNIP suppressed with Mel addition even in the miR-17-5p inhibitor cell model, resulting in the inactivation of NLRP3 inflammasome-dependent pyroptosis. Overall, we draw the conclusion as Mel attenuates Pb-induced intestinal epithelial cell pyroptosis via miR-17-5p/TXNIP axis. The present study provides a novel perspective for toxicological mechanism of Pb, and new insights for the detoxification mechanism of Mel.

Protective effect and mechanism of loganin and morroniside on acute lung injury and pulmonary fibrosis

BACKGROUND

Loganin and morroniside are two iridoid glycosides with anti-inflammatory, antioxidant and anti-tumor effects. Whether they have effect on acute lung injury and pulmonary fibrosis are still unknown.

PURPOSE

To explore the potential effects of loganin and morroniside against acute lung cancer and pulmonary fibrosis, and the underlying molecular mechanism.

STUDY DESIGN AND METHODS

Cell and animal models of acute lung injury were established by the induction of LPS. After intervention with loganin and morroniside, the pathological symptom of lung tissue was assessed, pro-inflammatory factors in cells and lung tissues were detected, NF- κB/STAT3 signaling pathway related proteins were detected by western blotting. Mice pulmonary fibrosis model was induced by bleomycin, pathological symptom was assessed by HE and Masson staining. Fibrosis related indicators were detected by qPCR or western blot. CD4+/CD8+ was detected by flow cytometry.

RESULTS

Loganin and morroniside relieved the pathological symptom of lung tissue in acute lung injury, pro-inflammatory factors such as IL-6, IL-1β, TNF-α mRNA were inhibited. Expression of p-p65 and STAT3 in lung tissues were also downregulated. In addition, loganin and morroniside downregulated the expression of collagen fiber, hydroxyproline and TGF-β1, collagen I and α-SMA mRNA in lung tissues of pulmonary fibrosis model. This study proved that loganin and morroniside have protective effect on acute lung injury and pulmonary fibrosis, and may provide theoretical basis for the development of new clinical drugs.

Simvastatin Inhibits NLRP3 Inflammasome Activation and Ameliorates Lung Injury in Hyperoxia-Induced Bronchopulmonary Dysplasia via the KLF2-Mediated Mechanism

Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly found in premature infants. Excessive inflammation and oxidative stress contribute to BPD occurrence and development. Simvastatin, as an inhibitor of HMG-CoA reductase, has been reported to have antioxidative and anti-inflammatory effects. However, its effect and possible mechanisms in hyperoxia-induced lung injury are rarely reported. In this study, in vivo and in vitro experiments were conducted to investigate whether simvastatin could ameliorate hyperoxia-induced lung injury and explore its potential mechanism. For the in vivo study, simvastatin could improve alveolar development after hyperoxic lung injury and reduce hyperoxic stress and inflammation. The in vitro study revealed that simvastatin can reduce inflammation in A549 cells after high-oxygen exposure. Simvastatin suppressed NLRP3 inflammasome activation and played anti-inflammatory and antioxidant roles by increasing KLF2 (Krüppel-like factor 2) expression. In vitro experiments also revealed that these effects of simvastatin were partially reversed by KLF2 shRNA, indicating that KLF2 was involved in simvastatin effects. In summary, our findings indicate that simvastatin could downregulate NLRP3 inflammasome activation and attenuate lung injury in hyperoxia-induced bronchopulmonary dysplasia via KLF2-mediated mechanism.

Immune Regulation of Heme Oxygenase-1 in Allergic Airway Inflammation

Heme oxygenase-1 (HO-1) is not only a rate-limiting enzyme in heme metabolism but is also regarded as a protective protein with an immunoregulation role in asthmatic airway inflammation. HO-1 exerts an anti-inflammation role in different stages of airway inflammation via regulating various immune cells, such as dendritic cells, mast cells, basophils, T cells, and macrophages. In addition, the immunoregulation role of HO-1 may differ according to subcellular locations.

S1P/S1P2 Signaling Axis Regulates Both NLRP3 Upregulation and NLRP3 Inflammasome Activation in Macrophages Primed with Lipopolysaccharide

The activation of NLRP3 inflammasome is a key factor for various inflammatory diseases. Here, we provide experimental evidence supporting the regulatory role of sphingosine-1-phosphate (S1P) in NLRP3 inflammasome activation in mouse bone-marrow-derived macrophages (BMDMs), along with the S1P receptor subtype involved and underlying regulatory mechanisms. During the priming stage, S1P induced NLRP3 upregulation in BMDMs only when primed with lipopolysaccharide (LPS). In this event, S1P₂, but not S1P₁, was involved based on the attenuated NLRP3 upregulation with JTE013 (S1P₂ antagonist) or S1P₂ knockdown. During the activation stage, S1P induced NLRP3 inflammasome activation in LPS-primed BMDMs via caspase-1 activation, interleukin 1β maturation, apoptosis-associated speck-like protein containing a CARD (ASC) speck formation, and IL-1β secretion. Such NLRP3 inflammasome activation was blocked by either pharmacological inhibition or genetic knockdown of S1P₂. NF-κB, PI3K/Akt, and ERK1/2 were identified as effector pathways underlying S1P/S1P₂ signaling in the regulation of NLRP3 upregulation in LPS-primed BMDMs. Further, reactive oxygen species (ROS) production was dependent on the S1P/S1P₂ signaling axis in these cells, and the ROS generated regulate NLRP3 inflammasome activation, but not NLRP3 priming. Collectively, our findings suggest that S1P promotes NLRP3 upregulation and NLRP3 inflammasome activation in LPS-primed BMDMs via S1P₂ and subsequent effector pathways.

Air Pollution and the Airways: Lessons from a Century of Human Urbanization

Since the industrial revolution, air pollution has become a major problem causing several health problems involving the airways as well as the cardiovascular, reproductive, or neurological system. According to the WHO, about 3.6 million deaths every year are related to inhalation of polluted air, specifically due to pulmonary diseases. Polluted air first encounters the airways, which are a major human defense mechanism to reduce the risk of this aggressor. Air pollution consists of a mixture of potentially harmful compounds such as particulate matter, ozone, carbon monoxide, volatile organic compounds, and heavy metals, each having its own effects on the human body. In the last decades, a lot of research investigating the underlying risks and effects of air pollution and/or its specific compounds on the airways, has been performed, involving both in vivo and in vitro experiments. The goal of this review is to give an overview of the recent data on the effects of air pollution on healthy and diseased airways or models of airway disease, such as asthma or chronic obstructive pulmonary disease. Therefore, we focused on studies involving pollution and airway symptoms and/or damage both in mice and humans.

Protective effect of combination of anakinra and MCC950 against acute lung injury is achieved through suppression of the NF-κB-mediated-MAPK and NLRP3-caspase pathways

BACKGROUND

It has been uncovered that the interleukin-1 receptor antagonist anakinra and the NLRP3 inflammasome blocker MCC950 can alleviate acute lung injury (ALI). However, the specific mechanism underlying these effects remains unknown. Thus, we sought to investigate the effects of anakinra and MCC950 in ALI as well as the molecular mechanisms.

METHODS

We treated C57BL/6 mice with aerosols of anakinra and/or MCC950 along with lipopolysaccharide (LPS), followed by mechanical ventilation (MV) treatment after 1.5 h of inhalation of aforementioned compounds. Lung injury was assessed by determining the level of inflammatory factors in the alveolar lavage fluid and monitoring blood oxygen saturation. We confirmed our findings of regulation of the ALI model through the nuclear factor-κB (NF-κB)/mitogen-activated protein kinase (MAPK)/nucleotide binding domain and leucine-rich repeat (NLR) pyrin domain containing 3 (NLRP3)-caspase pathway in further studies with RelA^-/- mice.

RESULTS

Combined treatment of anakinra and MCC950 presented the best therapeutic effect on LPS and MV-induced ALI than did treatment with anakinra or MCC950 alone. Combined therapy with anakinra and MCC950 suppressed MAPK and NLRP3-caspase via inhibition of the NF-κB pathway to improve ALI, but the therapeutic pathway was revoked by knockout of NF-κB.

CONCLUSION

Taken together, combined treatment of anakinra and MCC950 was effective in alleviating ALI in the mouse model, highlighting a new insight into ALI treatment.

Carbon Monoxide Releasing Molecule-3 Enhances Osteogenic Differentiation of Human Periodontal Ligament Stem Cells by Carbon Monoxide Release

Purpose

Limited intrinsic regeneration capacity following bone destruction remains a significant medical problem. Multiple regulatory effects of carbon monoxide releasing molecule-3 (CORM-3) have been reported. The aim of this study was to investigate the effect of CORM-3 on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) during osteogenesis.

Patients and Methods

hPDLSCs obtained from healthy periodontal ligament tissues were cultured and identified with specific surface antigens by flow cytometry. Effect of CORM-3 on the proliferation of hPDLSCs was determined by CCK-8 assay. Alizarin red staining and alkaline phosphatase (ALP) activity were used to assess the osteogenic differentiation of hPDLSCs. Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis were used to detect the expression of the indicated genes. Critical-sized skull defect was made in Balb/c-nude mice, microcomputed tomography (Micro-CT) and Masson trichrome staining were used to assess the new bone regeneration in mice.

Results

CORM-3 (400 μmol/l) significantly promoted the proliferation of hPDLSCs. CORM-3 pretreatment not only notably enhanced the mRNA and protein expression of osteo-specific marker OPN, Runx2 and ALP, but also increased mineral deposition and ALP activity by the release of CO on day 3, 7 and 14 (P<0.05). Degassed CORM-3 did not show the same effect as CORM-3. In animal model, application of CORM-3 with hPDLSCs transplantation highly increased new bone formation in skull defect region.

Conclusion

CORM-3 promoted osteogenic differentiation of hPDLSCs, and increased hPDLSCs-induced new bone formation in mice with critical-sized skull defect, which suggests an efficient and promising strategy in the treatment of disease with bone defect.

Role of pirfenidone in TGF-β pathways and other inflammatory pathways in acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection: a theoretical perspective

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes pulmonary injury or multiple-organ injury by various pathological pathways. Transforming growth factor-beta (TGF-β) is a key factor that is released during SARS-CoV-2 infection. TGF-β, by internalization of the epithelial sodium channel (ENaC), suppresses the anti-oxidant system, downregulates the cystic fibrosis transmembrane conductance regulator (CFTR), and activates the plasminogen activator inhibitor 1 (PAI-1) and nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-kB). These changes cause inflammation and lung injury along with coagulopathy. Moreover, reactive oxygen species play a significant role in lung injury, which levels up during SARS-CoV-2 infection.

Drug Suggestion

Pirfenidone is an anti-fibrotic drug with an anti-oxidant activity that can prevent lung injury during SARS-CoV-2 infection by blocking the maturation process of transforming growth factor-beta (TGF-β) and enhancing the protective role of peroxisome proliferator-activated receptors (PPARs). Pirfenidone is a safe drug for patients with hypertension or diabetes and its side effect tolerated well.

Conclusion

The drug as a theoretical perspective may be an effective and safe choice for suppressing the inflammatory response during COVID-19. The recommendation would be a combination of pirfenidone and N-acetylcysteine to achieve maximum benefit during SARS-CoV-2 treatment.

Potential of Forsythoside I as a therapeutic approach for acute lung injury: Involvement of TXNIP/NLRP3 inflammasome

OBJECTIVE

To explore the role of Forsythoside I (FI) in acute lung injury (ALI) mouse and its underling mechanism.

METHODS

The cell models of ALI are constructed by LPS induction. After pretreatment with different concentrations of FI, the lung injury is assessed by pathological changes of lung tissues and cell apoptosis. The cell viability, levels of pro-inflammatory cytokines, and the activation of TXNIP/NLRP3 pathway are inspected to investigate whether the effect of FI on inflammatory response is exerted by regulating the TXNIP/NLRP3 pathway.

RESULTS

LPS induces inflammatory cell infiltration, tissue necrosis and pulmonary interstitial edema of mouse tissues, and LPS increases the protein concentration and levels of pro-inflammatory factors in mouse BALF. Additionally, enhanced cell apoptotic level, increased W/D ratio and MPO activity, as well as suppressed SOD activity are observed in LPS-induced mouse models. Those inflammation response, oxidative stress and lung injury can be attenuated by FI (12.5 mg/kg, 25 mg/kg, 50 mg/kg) in a dose-dependent manner. Meanwhile, both in vitro and in vivo studies reveal that FI can lead to suppressed TXNIP expression and inactivated NLRP3 inflammasomes. TXNIP is an upstream target of NLRP3, and FI mitigates ALI by decreasing TXNIP to block NLRP3 inflammasomes.

CONCLUSION

FI protects against ALI through the mediation of TXNIP/NLRP3 inflammasome axis and therefore has a certain potential for ALI treatment.

Carbon monoxide-triggered health effects: the important role of the inflammasome and its possible crosstalk with autophagy and exosomes

Carbon monoxide (CO) has long been known as a "silent killer" because of its ability to bind hemoglobin (Hb), leading to reduced oxygen carrying capacity of Hb, which is the main cause of CO poisoning (COP) in humans. Emerging studies suggest that mitochondria is a key target of CO action that can impact key biological processes, including apoptosis, cellular proliferation, inflammation, and autophagy. Despite its toxicity at high concentrations, CO also exhibits cyto- and tissue-protective effects at low concentrations in animal models of organ injury and disease. Specifically, CO modulates the production of pro- or anti-inflammatory cytokines and mediators by regulating the NLRP3 inflammasome. Given that human diseases are strongly associated with inflammation, a deep understanding of the exact mechanism is helpful for treatment. Autophagic factors and inflammasomes interact in various situations, including inflammatory disease, and exosomes might function as the bridge between the inflammasome and autophagy activation. Thus, the interplay among autophagy, mitochondrial dysfunction, exosomes, and the inflammasome may play pivotal roles in the health effects of CO. In this review, we summarize the latest research on the beneficial and toxic effects of CO and their underlying mechanisms, focusing on the important role of the inflammasome and its possible crosstalk with autophagy and exosomes. This knowledge may lead to the development of new therapies for inflammation-related diseases and is essential for the development of new therapeutic strategies and biomarkers of COP.

Overexpression of Limb Bud and Heart Alleviates Sepsis-Induced Acute Lung Injury via Inhibiting the NLRP3 Inflammasome

Objective

Sepsis is a leading cause of acute lung injury (ALI). This study attempted to investigate the effects of limb bud and heart (LBH) on the development of sepsis-induced ALI and its underlying mechanism of action.

Methods

The sepsis-induced ALI mouse model was established by cecal ligation and puncture (CLP). The lung injury score and lung wet/dry weight (W/D) ratio were used to evaluate the lung injury. In vitro, ALI was simulated by lipopolysaccharide (LPS) treatment in A549 cells. The mRNA expression of LBH, NLRP3, ASC, and proinflammatory cytokines was measured by qRT-PCR. The viability of LPS-induced A549 cells was analyzed by MTT assay. Furthermore, western blot was performed to detect the protein expression of LBH, NLRP3, and ASC. LPS-induced A549 cells were treated with MCC950 (NLRP3 inflammasome inhibitor) to confirm the effect of LBH on NLRP3 inflammasome.

Results

The mRNA and protein expression of LBH was decreased in sepsis-induced ALI. LBH overexpression reduced the lung injury score, lung W/D ratio, expression of proinflammatory cytokines, and NLRP3 inflammasome activation in sepsis-induced ALI mouse model. Additionally, LBH upregulation increased the viability, while it decreased the proinflammatory cytokine expression and NLRP3 inflammasome activation of LPS-induced A549 cells. Moreover, MCC950 reversed the promoting effects of LBH silencing on proinflammatory cytokine expression and NLRP3 inflammasome activation in LPS-induced A549 cells.

Conclusions

LBH alleviated lung injury in sepsis-induced ALI mouse model by inhibiting inflammation and NLRP3 inflammasome, and restrained the inflammation by inhibiting NLRP3 inflammasome in LPS-induced A549 cells, providing a novel therapeutic target for ALI.

Orientin relieves lipopolysaccharide-induced acute lung injury in mice: The involvement of its anti-inflammatory and anti-oxidant properties

Oxidative stress and inflammatory responses are nearly involved in the pathogenesis of various diseases, including acute lung injury (ALI). Orientin (Ori), a flavonoid component extracted from natural plants, displayed anti-inflammatory and antioxidant properties in our previous studies. In the current study, we aimed to investigate the amelioration effect of Ori on lipopolysaccharide (LPS)-induced ALI, and we further explored the potential molecular mechanisms. The present results indicated that Ori effectively alleviated LPS-induced ALI by improving the histological changes of lung; decreasing the lung W/D ratio and protein levels, the release of inflammatory cells and cytokines into the bronchoalveolar lavage fluid (BALF); inhibiting nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and high mobility group box 1 (HMGB1) protein expression; reducing malondialdehyde (MDA) formation and reactive oxygen species (ROS) generation; and increasing the content of glutathione (GSH) and superoxide dismutase (SOD) contents. Moreover, Ori treatment not only significantly suppressed the LPS-induced nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome, and nuclear factor-kappa B (NF-κB) signaling pathway activation, but also obviously restored the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), NAD (P) H: quinone oxidoreductase (NQO1), glutamate-cysteine ligase catalytic (GCLC), and heme oxygenase 1 (HO-1) expression in the lung; all of which are reduced by LPS. Taken together, these data suggested that Ori plays an important role in the protection against ALI by suppressing inflammation and oxidative stress which may be strongly related to the suppression of NLRP3 inflammasome and NF-κB activation, as well as the upregulation of the Nrf2 signaling pathway.

Preparation of resveratrol dry suspension and its immunomodulatory and anti-inflammatory activity in mice

Context: Resveratrol is a natural polyphenol compound. It exhibits antitumor, immunostimulatory, and antiviral activities. However, poor water solubility and structural instability limit its administration and storage.Objective: A resveratrol dry suspension (RDS) was prepared and immunomodulatory effect in immunosuppressive mice induced by cyclophosphamide and anti-inflammatory activities in mice were evaluated.Materials and methods: The preparation of RDS was optimized by the orthogonal design method. To evaluate the immunomodulatory effects, SPF Kunming mice were divided into seven groups comprising of nine males and nine females for each group. The RDS supplemented group was administrated doses of 3.33, 1.67, and 0.83 g/kg/d. Then visceral index, lymphocyte proliferation, the ratio of CD3⁺ CD4⁺/CD3⁺ CD8⁺, and the contents of cytokines in serum were tested. To ameliorate effects of acetic acid induced capillary permeability, xylene-based ear oedema, and cotton pellet granuloma, RDS as anti-inflammatory agent was administered at doses of 1, 0.33, and 0.1 g/kg/d as compared to indomethacin (IM) provided as a positive control at 10 mg/kg.Results: RDS inhibited the degradation of resveratrol and enhanced the CD3⁺ CD4⁺/CD3⁺ CD8⁺ ratio, spleen index, IL-2 level, and splenic lymphocytes in immunosuppressive mice. RDS (0.1 g/kg/d) significantly inhibited the acetic acid-induced capillary permeability, and at doses of 0.33 and 1 g/kg/d repressed the ear swelling and granuloma formation in immunocompromised mice.Discussion and Conclusion: RDS is a stable, cheaper, and suitable preparation with potent immunoregulatory and anti-inflammatory activities. Keeping in view these remarkable properties, RDS could be an appropriate preparation for clinic use of resveratrol.

Modulation of Inflammation and Immune Responses by Heme Oxygenase-1: Implications for Infection with Intracellular Pathogens

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme molecules releasing equimolar amounts of biliverdin, iron and carbon monoxide. Its expression is induced in response to stress signals such as reactive oxygen species and inflammatory mediators with antioxidant, anti-inflammatory and immunosuppressive consequences for the host. Interestingly, several intracellular pathogens responsible for major human diseases have been shown to be powerful inducers of HO-1 expression in both host cells and in vivo. Studies have shown that this HO-1 response can be either host detrimental by impairing pathogen control or host beneficial by limiting infection induced inflammation and tissue pathology. These properties make HO-1 an attractive target for host-directed therapy (HDT) of the diseases in question, many of which have been difficult to control using conventional antibiotic approaches. Here we review the mechanisms by which HO-1 expression is induced and how the enzyme regulates inflammatory and immune responses during infection with a number of different intracellular bacterial and protozoan pathogens highlighting mechanistic commonalities and differences with the goal of identifying targets for disease intervention.

NLRP3 Inflammasome Activation Is Involved in LPA1-Mediated Brain Injury after Transient Focal Cerebral Ischemia

Lysophosphatidic acid receptor 1 (LPA₁) contributes to brain injury following transient focal cerebral ischemia. However, the mechanism remains unclear. Here, we investigated whether nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation might be an underlying mechanism involved in the pathogenesis of brain injury associated with LPA₁ following ischemic challenge with transient middle cerebral artery occlusion (tMCAO). Suppressing LPA₁ activity by its antagonist attenuated NLRP3 upregulation in the penumbra and ischemic core regions, particularly in ionized calcium-binding adapter molecule 1 (Iba1)-expressing cells like macrophages of mouse after tMCAO challenge. It also suppressed NLRP3 inflammasome activation, such as caspase-1 activation, interleukin 1β (IL-1β) maturation, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) speck formation, in a post-ischemic brain. The role of LPA₁ in NLRP3 inflammasome activation was confirmed in vitro using lipopolysaccharide-primed bone marrow-derived macrophages, followed by LPA exposure. Suppressing LPA₁ activity by either pharmacological antagonism or genetic knockdown attenuated NLRP3 upregulation, caspase-1 activation, IL-1β maturation, and IL-1β secretion in these cells. Furthermore, nuclear factor-κB (NF-κB), extracellular signal-regulated kinase 1/2 (ERK1/2), and p38 were found to be LPA₁-dependent effector pathways in these cells. Collectively, results of the current study first demonstrate that LPA₁ could contribute to ischemic brain injury by activating NLRP3 inflammasome with underlying effector mechanisms.

Mangiferin inhibits lipopolysaccharide-induced epithelial-mesenchymal transition (EMT) and enhances the expression of tumor suppressor gene PER1 in non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) is often complicated by pulmonary infection, which affects treatment and prognosis. Bacterial lipopolysaccharide (LPS) is an effective stimulator of inflammatory cytokine production, and previous studies have reported that LPS promotes tumor invasion and metastasis. Mangiferin is a plant-derived C-glucosylxanthone with many biological activities, such as antioxidation and anti-inflammation. This research mainly explored the mechanism of its antitumor activities on LPS-induced A549, NCI-H460, and NCI-H520 NSCLC cells. We determined that mangiferin exhibits growth inhibiting activity against LPS-induced NSCLC cells through the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. In addition, mangiferin reversed the LPS-induced downregulation of E-cadherin (epithelial marker); conversely, it significantly inhibited the expression of raised vimentin (mesenchymal markers). Moreover, the ability of NSCLC cells to migrate, as evidenced by the wound healing and transwell migration assays, and the expression of CXCR4 increased by LPS were significantly repressed by mangiferin. In addition, mangiferin markedly mediated protein levels of PER1 and NLRP3 in LPS-induced NSCLC cells and reduced the secretion of IL-1β. These results indicate that mangiferin is not only a remarkable anti-inflammatory compound but also an antitumor agent; thus, it has the potential for being developed into anti-inflammatory and antitumor drugs in the future.

TXNIP/TBP-2: A Master Regulator for Glucose Homeostasis

Identification of thioredoxin binding protein-2 (TBP-2), which is currently known as thioredoxin interacting protein (TXNIP), as an important binding partner for thioredoxin (TRX) revealed that an evolutionarily conserved reduction-oxidation (redox) signal complex plays an important role for pathophysiology. Due to the reducing activity of TRX, the TRX/TXNIP signal complex has been shown to be an important regulator for redox-related signal transduction in many types of cells in various species. In addition to its role in redox-dependent regulation, TXNIP has cellular functions that are performed in a redox-independent manner, which largely rely on their scaffolding function as an ancestral α-Arrestin family. Both the redox-dependent and -independent TXNIP functions serve as regulatory pathways in glucose metabolism. This review highlights the key advances in understanding TXNIP function as a master regulator for whole-body glucose homeostasis. The potential for therapeutic advantages of targeting TXNIP in diabetes and the future direction of the study are also discussed.

Resuscitation with PEGylated carboxyhemoglobin preserves renal cortical oxygenation and improves skeletal muscle microcirculatory flow during endotoxemia

PEGylated carboxyhemoglobin (PEGHbCO), which has carbon monoxide-releasing properties and plasma expansion and oxygen-carrying properties, may improve both skeletal microcirculatory flow and renal cortical microcirculatory Po₂ (CµPo₂) and, subsequently, limit endotoxemia-induced acute kidney injury. Anesthetized, ventilated Wistar albino rats (n = 44) underwent endotoxemic shock. CµPo₂ was measured in exposed kidneys using a phosphorescence-quenching method. Rats were randomly assigned to the following five groups: 1) unresuscitated lipopolysaccharide (LPS), 2) LPS + Ringer's acetate (RA), 3) LPS + RA + 0.5 µg·kg·^-1min^-1 norepinephrine (NE), 4) LPS + RA + 320 mg/kg PEGHbCO, and 5) LPS + RA + PEGHbCO + NE. The total volume was 30 mL/kg in each group. A time control animal group was used. Skeletal muscle microcirculation was assessed by handheld intravital microscopy. Kidney immunohistochemistry and myeloperoxidase-stained leukocytes in glomerular and peritubular areas were analyzed. Endotoxemia-induced histological damage was assessed. Plasma levels of IL-6, heme oxygenase-1, malondialdehyde, and syndecan-1 were assessed by ELISA. CµPo₂ was higher in the LPS + RA + PEGHbCO-resuscitated group, at 35 ± 6mmHg compared with 21 ± 12 mmHg for the LPS+RA group [mean difference: -13.53, 95% confidence interval: (-26.35; -0.7156), P = 0.035]. The number of nonflowing, intermittent, or sluggish capillaries was smaller in groups infused with PEGHbCO compared with RA alone (P < 0.05), while the number of normally perfused vessels was greater (P < 0.05). The addition of NE did not further improve CµPo₂ or microcirculatory parameters. Endotoxemia-induced kidney immunohistochemistry and histological alterations were not mitigated by PEGHbCO 1 h after resuscitation. Renal leukocyte infiltration and plasma levels of biomarkers were similar across groups. PEGHbCO enhanced CµPo₂ while restoring skeletal muscle microcirculatory flow in previously nonflowing capillaries. PEGHbCO should be further evaluated as a resuscitation fluid in mid- to long-term models of sepsis-induced acute kidney injury.

Metformin protects against intestinal ischemia-reperfusion injury and cell pyroptosis via TXNIP-NLRP3-GSDMD pathway

Intestinal ischemia-reperfusion (I/R) injury is a life-threatening vascular emergency and has long been a disturbing problem for surgeons. Oxidative stress is considered a vital factor in I/R injury. Metformin has anti-oxidative properties and protects against I/R injury. The present study aimed to investigate whether Metformin protects against intestinal I/R injury and reveal the protective mechanism of Metformin. I/R injury was induced in mice by temporary superior mesenteric artery occlusion, and Caco-2 cells were subjected to OGD/R to establish an in vitro model. Different doses of Metformin were administered in vivo and in vitro. We found that I/R injury led to intestinal barrier disruption and cell death by examining histopathological results and the intestinal barrier index, including TER, tight junction proteins and serum biomarkers. We confirmed the existence of pyroptosis in intestinal I/R injury. Moreover, we confirmed the role of pyroptosis in intestinal I/R injury by silencing the gasdermin D (GSDMD). Then, we confirmed that Metformin treatment protected barrier function against intestinal I/R injury and reduced oxidative stress and the inflammatory response. Importantly, Metformin reduced pyroptosis-related proteins, including NLRP3, cleaved caspase-1, and the N-terminus of GSDMD. Knocking down the GSDMD could reversed the protective effects of Metformin, which showed pyroptosis was one of the major cell death pathways controlled by Metformin treatment in setting of intestinal I/R injury. We also discovered that Metformin suppressed the expression of TXNIP and the interaction between TXNIP and NLRP3. We performed siRNA knockdown and found that the protective effects were abolished, which further confirmed our findings. In conclusion, we believe that Metformin protects against intestinal I/R injury in a TXNIP-NLRP3-GSDMD-dependent manner.

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Pyroptosis plays an important role in intestinal I/R injury.

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Metformin protects against intestinal I/R injury in mice.

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Metformin protects Caco-2 cells subjected to OGD/R.

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Metformin inhibits pyroptosis, inflammation and oxidative stress during I/R injury.

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Metformin exerts protective effect through TXNIP-NLRP3-GSDMD pathway.

Knockdown of Long Noncoding RNAs of Maternally Expressed 3 Alleviates Hyperoxia-Induced Lung Injury via Inhibiting Thioredoxin-Interacting Protein-Mediated Pyroptosis by Binding to miR-18a

Long-term hyperoxia exposure may cause lung damage with characteristic inflammation. Long noncoding RNA of maternally expressed 3 (MEG3) is up-regulated in lung tissues exposed to hyperoxia; however, the underlying mechanism is unclear. Hyperoxia-induced cells and mouse models were used to study these mechanisms. Molecular assays were used to detect cell viability, cytotoxicity, and expression of miR-18a, MEG3, and inflammatory cytokines. The interaction among MEG3, miR-18a, and thioredoxin-interacting protein (TXNIP) was verified; and pyroptosis-related proteins were analyzed. The in vivo model was established by exposing MEG3 knockdown mice to hyperoxia. Hematoxylin and eosin staining was used to assess pathologic alterations of lung tissues. Hyperoxia suppressed cell viability, induced cell damage, and exacerbated the secretion of IL-1β and IL-18. Hyperoxia inhibited miR-18a, with increased expression of MEG3, TXNIP, and nonobese diabetic-like receptor family pyrin domain containing 3 (NLRP3). MEG3 aggravated TXNIP expression by binding to miR-18a. Knockdown of MEG3 rescued hyperoxia-induced pyroptosis by up-regulating miR-18a. Furthermore, knockdown of MEG3 inhibited NLRP3 inflammasome activity and caspase-1 signaling by miR-18a. In vivo knockdown of MEG3 and overexpression of miR-18a relieved hyperoxia-induced lung injury via restraining NLRP3 inflammasome-mediated pyroptosis, whereas miR-18a inhibition reversed these effects. In conclusion, knockdown of MEG3 inhibits pyroptosis to alleviate hyperoxia lung injury by suppressing NLRP3 inflammasome and caspase-1 signaling via regulating miR-18a-TXNIP axis.

NecroX-5 alleviate lipopolysaccharide-induced acute respiratory distress syndrome by inhibiting TXNIP/NLRP3 and NF-κB

The activation of NLRP3 inflammasome and NF-κB pathway, associating with oxidativestress, have been implicated in the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). NecroX-5 has been reported to exhibit theeffectsofanti-oxidation and anti-stress in various diseases. However, the role of NecroX-5 in ALI has not been explicitly demonstrated. The aim of this study was to explore the therapeutic effects and potential mechanism action of NecroX-5 on ALI. Here, we found that NecroX-5 pretreatment dramatically diminished the levels of IL-1β, IL-18 and ROS in in RAW264.7 cells challenged with LPS and ATP. Furthermore, NecroX-5 suppressed the activation of NLRP3 inflammasome and NF-κB signalpathway. In addition, NecroX-5 also inhibited the thioredoxin-interacting protein (TXNIP) expression. In vivo, NecroX-5 reduced the LPS-induced lung histopathological injury, the number of TUNEL-positive cells, lung wet/dry (W/D) ratio, levels of total protein and inflammatory cytokines in the bronchoalveolar lavage fluid (BALF) in mice. Additionally, LPS-induced upregulation of myeloperoxidase (MPO), ROS production and malondialdehyde (MDA) were inhibited by NecroX-5 administration. Thus, our results demonstrate that NecroX-5 protects against LPS-induced ALI by inhibiting TXNIP/NLRP3 and NF-κB.

Heme oxygenase-1/carbon monoxide as modulators of autophagy and inflammation

Heme oxygenase-1 (HO-1) catalyzes heme degradation to generate biliverdin-IXα, carbon monoxide (CO), and iron. The HO-1/CO system confers cytoprotection in animal models of organ injury and disease, via modulation of inflammation and apoptosis. Recent studies have uncovered novel anti-inflammatory targets of HO-1/CO including regulation of the autophagy and inflammasome pathways. Autophagy is a lysosome-dependent program for the turnover of cellular organelles such as mitochondria, proteins, and pathogens; which may downregulate inflammatory processes. Therapeutic modulation of autophagy by CO has been demonstrated in models of sepsis. The nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome regulates the maturation of pro-inflammatory cytokines. CO can regulate NLRP3 inflammasome activation and associated pro-inflammatory cytokines production and promote the resolution of inflammation by upregulating the synthesis of specialized pro-resolving mediators (SPMs). Mitochondria may represent a proximal target of HO-1/CO action. HO-1 may localize to mitochondria in response to stress, while CO can moderate mitochondrial dysfunction and regulate mitochondrial autophagy (mitophagy) and biogenesis. The interplay between mitochondrial autophagy, mitochondrial dysfunction, and the regulation and resolution of inflammation may make important contributions to the protection afforded by HO-1/CO in cellular and organ injury models. Recent studies have continued to explore the potential of CO for clinical applications.

AMPK as a potential pharmacological target for alleviating LPS-induced acute lung injury partly via NLRC4 inflammasome pathway inhibition

Old people are spectacularly susceptible to acute lung injury (ALI) and the accompanying complications. An acute aggravated inflammatory response is a characteristic feature of ALI, and inflammasomes play a critical role in the inflammatory response. Metformin has been shown to be an effective anti-inflammatory agent in ALI. However, the mechanism of this regulation still remains poorly understood. In this study, 18- to 19-month-old male mice were treated by intratracheal instillation of lipopolysaccharide (LPS) or PBS with or without metformin pretreatment. We found that the metformin pretreatment alleviated the lung injury and decreased the levels of TNF-a, IL-1β and IL-6 in the bronchoalveolar lavage fluid (BALF) and in lung tissues, as well as the levels of NLRP3, NLRC4 and cleaved caspase-1 associated with LPS-induced ALI in old mice. Furthermore, the in vitro study showed metformin dose-dependently suppressed NLRC4 inflammasome expression. Metformin activated AMPK by phosphorylation; thus, we investigated the role of AMPK in NLRC4 activation. The results demonstrated that the efficacy of metformin was reduced when using the AMPK pharmacological inhibitor compound C or AMPKα₁ expression was knocked down in RAW 264.7 cells. In conclusion, our data indicated that metformin may inhibit NLRC4 inflammasome activation in LPS-induced ALI in old mice through AMPK signaling, and further understanding of the AMPK/NLRC4 axis may provide a novel therapeutic strategy for LPS-induced ALI in the future.

The Defensive Action of LYRM03 on LPS-Induced Acute Lung Injury by NF-κB/TLR4/NLRP3 Signals

The aim of the current investigation was to study the role of 3-amino-2-hydroxy-4-phenyl-valyl-isoleucine (LYRM03) in lipopolysaccharide (LPS)-induced acute lung injury (ALI) and investigate its potential pathogenesis. An LPS-induced ALI model was produced with LPS (5 mg/kg) followed by 24 h of injury. Rats were randomly assigned to 6 groups for in vivo experiments: (1) Sham, (2) LYRM03 (20 mg/kg), (3) LPS, (4) LPS plus LYRM03 (5 mg/kg), (5) LPS plus LYRM03 (10 mg/kg), and (6) LPS plus LYRM03 (20 mg/kg). The rat alveolar macrophage cell line (NR8383) cells were divided into 6 groups for in vitro experiments: (1) Sham, (2) LYRM03 (200 μmol/L), (3) LPS (100 ng/mL), (4) LPS plus LYRM03 (50 μmol/L), (5) LPS plus LYRM03 (100 μmol/L), and (6) LPS plus LYRM03 (200 μmol/L). Further study about siRNA targeting NF-κB p65, TLR4, and NLRP3 to explore the potential mechanism of LYRM03 in the LPS-induced ALI models have been done. Therefore, LYRM03 decreased LPS-induced ALI and NR8383 activation as demonstrated through hematoxylin-eosin staining and western blot analysis in vivo and in vitro. LYRM03 ameliorated the content of protein in bronchoalveolar lavage fluid, myeloperoxidase in the lung and malondialdehyde (MDA) in serum. In addition, LYRM03 ameliorated the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-18 (IL-18) in the serum of rats and the supernatant of NR8383 cells. Moreover, LYRM03 significantly inhibited the activities of nuclear factor kappa B (NF-κB), myeloid differentiation factor 88 (MyD88), and toll-like receptor 4 (TLR4). LYRM03 also reduced the increase in the inflammasome, including apoptosis-related speck-like protein containing CARD (ASC), and NOD-like receptor 3 (NLRP3), in LPS-stimulated rats and NR8383 cells. The extent of injury and lung injury scores in the LYRM03 (20 mg/kg) + siRNA targeting NF-κB p65, TLR4, or NLRP3 + LPS-treated rats were higher than that in the LYRM03 (20 mg/kg) + LPS-treated rats. In summary, LYRM03 conferred an intensely lung defensive action on LPS-induced ALI in vivo and in vitro, which could be associated with the abatement of TLR4-induced NLRP3/NF-κB.

Carbon monoxide releasing molecule-2 protects against particulate matter-induced lung inflammation by inhibiting TLR2 and 4/ROS/NLRP3 inflammasome activation

Exposure to airborne particulate matter (PM) not only causes lung inflammation and chronic respiratory diseases, but also increases the incidence and mortality of cardiopulmonary diseases. The nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome activation has been shown to play a critical role in the formation of many chronic disorders. On the other hand, carbon monoxide (CO) has been shown to possess anti-inflammatory and antioxidant effects in many tissues and organs. Here, we investigated the effects and mechanisms of carbon monoxide releasing molecule-2 (CORM-2) on PM-induced inflammatory responses in human pulmonary alveolar epithelial cells (HPAEpiCs). We found that PM induced C-reactive protein (CRP) expression, NLRP3 inflammasome activation, IL-1β secretion, and caspase-1 activation, which were inhibited by pretreatment with CORM-2. In addition, transfection with siRNA of Toll-like receptor 2 (TLR2) or TLR4 and pretreatment with an antioxidant (N-acetyl-cysteine, NAC), the inhibitor of NADPH oxidase (diphenyleneiodonium, DPI), or a mitochondria-specific superoxide scavenger (MitoTEMPO) reduced PM-induced inflammatory responses. CORM-2 also inhibited PM-induced NADPH oxidase activity and NADPH oxidase- and mitochondria-derived ROS generation. However, pretreatment with inactivate CORM-2 (iCORM-2) had no effects on PM-induced inflammatory responses. Finally, we showed that CORM-2 inhibited PM-induced CRP, NLRP3 inflammasome, and ASC protein expression in the lung tissues of mice and IL-1β levels in the serum of mice. PM-enhanced leukocyte count in bronchoalveolar lavage fluid in mice was reduced by CORM-2. The results of this study suggested a protective role of CORM-2 in PM-induced lung inflammation by inhibiting the TLR2 and TLR4/ROS-NLRP3 inflammasome-CRP axial.

The Overexpression of Sirtuin1 (SIRT1) Alleviated Lipopolysaccharide (LPS)-Induced Acute Kidney Injury (AKI) via Inhibiting the Activation of Nucleotide-Binding Oligomerization Domain-Like Receptors (NLR) Family Pyrin Domain Containing 3 (NLRP3) Inflammasome

Background

Sepsis-induced acute kidney injury (AKI) is threatening the patients with sepsis, and nucleotide-binding oligomerization domain-like receptors (NLR) family pyrin domain containing 3 (NLRP3) inflammasome is considered to play a critical role in this complication of sepsis and might be regulated by sirtuin1 (SIRT1). Thus, we explored the roles of NLRP3 and SIRT1 in the lipopolysaccharide (LPS)-induced AKI in the HK-2 cell line.

Material/Methods

Cell viability was assessed by Cell Counting Kit-8 (CCK-8). Apoptosis rate was measured by flow cytometry. Protein levels of interleukin (IL)-1β and IL-18 were tested by enzyme-linked immunosorbent assay (ELISA) and NLRP3, cleaved caspase-1, caspase-1 were tested by western blot. The mRNA levels of IL-1β, IL-18, and SIRT1 were quantified by qPCR.

Results

LPS could decrease cell viability and the expression of SIRT1 and elevate the expressions of IL-1β, IL-18, NLRP3, and cleaved caspase-1. However, the overexpression of SIRT1 could upregulate cell viability and expression of caspase-1 and downregulate apoptosis rate, expressions of NLRP3, IL-1β, IL-18, and cleaved caspase-1.

Conclusions

NLRP3 inflammasome could act as a critical regulator promoting the process of AKI induced by LPS, and the overexpression of SIRT1 might be able to suppress the activation of NLRP3 and therefore resist the kidney injury, showing promise to be used as a target in the treatment of sepsis-induced AKI.

MicroRNA‑223 attenuates LPS‑induced inflammation in an acute lung injury model via the NLRP3 inflammasome and TLR4/NF‑κB signaling pathway via RHOB

Acute lung injury (ALI) and the more severe acute respiratory distress syndrome are common and complex inflammatory lung diseases. MicroRNAs (miRs) have emerged as novel gene regulatory molecules, serving a crucial role in a variety of complex diseases, including ALI. In the present study, the anti‑inflammatory action of miR‑223 on inflammation in ALI was demonstrated and the possible mechanism was further examined. In lipopolysaccharide‑induced ALI, the expression of miR‑223 was reduced compared with that in the control normal group. An in vitro model was used to analyze the effect of miR‑223 downregulation on an ALI model, which increased inflammation, and induced the activation of the NACHT, LRR and PYD domains‑containing protein 3 (NLRP3) inflammasome and Toll‑like receptor 4 (TLR4)/nuclear factor (NF)‑κB signaling pathway via rho‑related GTP‑binding protein RhoB (RHOB). In addition, the overexpression of miR‑223 reduced inflammation and suppressed the NLRP3 inflammasome and TLR4/NF‑κB signaling pathway via RHOB in the in vitro model. Furthermore, TLR4 inhibitor or NLRP3 inhibitor reduced the pro‑inflammatory effect of miR‑223 downregulation in ALI. In conclusion, the results of the present study indicated that miR‑223 functioned as a biological indicator by regulating inflammation in ALI, and may represent a novel potential therapeutic target and prognostic marker of ALI.

GYY4137 attenuates LPS-induced acute lung injury via heme oxygenase-1 modulation

GYY4137, a slow-releasing hydrogen sulfide (H₂S) donor, has been reported to exert anti-inflammatory activity and protect against sepsis. Heme oxygenase-1 (HO-1) is an important anti-inflammatory heat shock protein and plays a similar effect on sepsis. This study investigated the role of GYY4137 in acute lung injury (ALI) via HO-1 regulation. Lung injury was assessed in mice challenged with intratracheal lipopolysaccharide (LPS) and the mechanism of anti-inflammatory effects of GYY4137 was investigated in mice and RAW264.7 cells. GYY4137 reduced the LPS-mediated pulmonary injury and neutrophil infiltration, and inhibited the LPS-induced production of proinflammatory cytokines, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression. Moreover, GYY4137 suppressed the LPS-evoked NF-κB activation in RAW264.7 cells. GYY4137, not time-expired GYY4137 significantly induced HO-1 expression compared with the LPS group. The beneficial effects of GYY4137 above were reversed by the HO-1 inhibitor tin protoporphyrin (SnPP). These results suggest an anti-inflammatory effect and a therapeutic role of GYY4137 in LPS-induced ALI via HO-1 regulation.

Blocking the REDD1/TXNIP axis ameliorates LPS-induced vascular endothelial cell injury through repressing oxidative stress and apoptosis

The aim of the present study was to investigate the potential role of regulated in development and DNA damage response 1 (REDD1) in LPS-induced vascular endothelial injury by using human umbilical vein endothelial cells (HUVECs). We observed that REDD1 expression was apparently elevated in HUVECs after exposure to LPS. Additionally, elimination of REDD1 strikingly attenuated the secretion of the proinflammatory cytokines TNF-α, IL-6, IL-1β, and monocyte chemotactic protein-1 and the endothelial cell adhesion markers ICAM-1 and VCAM-1 that was induced by LPS stimulation. Subsequently, knockdown of REDD1 augmented cell viability but ameliorated lactate dehydrogenase release in HUVECs stimulated with LPS. Meanwhile, depletion of REDD1 effectively restricted LPS-induced HUVEC apoptosis, as exemplified by reduced DNA fragmentation, and it also elevated antiapoptotic Bcl-2 protein, concomitant with reduced levels of proapoptotic proteins Bax and cleaved caspase-3. Furthermore, repression of REDD1 remarkably alleviated LPS-triggered intracellular reactive oxygen species generation accompanied by decreased malondialdehyde content and increased the activity of the endogenous antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. Most important, depletion of REDD1 protected HUVECs against inflammation-mediated apoptosis and oxidative damage partly through thioredoxin-interacting protein (TXNIP). Collectively, these findings indicate that blocking the REDD1/TXNIP axis repressed the inflammation-mediated vascular injury process, which may be closely related to oxidative stress and apoptosis in HUVECs, implying that the REDD1/TXNIP axis may be a new target for preventing the endothelial cell injury process.

Oncogenic microRNA-411 promotes lung carcinogenesis by directly targeting suppressor genes SPRY4 and TXNIP

Lung cancer is one of the most common malignant diseases globally, composed of non-small cell lung cancer (NSCLC, 85%) and small cell lung cancer (SCLC, 15%). MicroRNAs (miRNAs) are single-stranded noncoding RNAs having important roles in lung cancer development. miR-411-5p/3p were reported to be increased significantly in human NSCLC tissues and cell lines. Moreover, miR-411-5p/3p overexpression could accelerate cell proliferation and migration, and impede cell apoptosis in NSCLC cell lines. Mechanically, SPRY4 is confirmed a direct target of miR-411-5p/3p. Furthermore, our findings showed that miR-411-5p/3p promoted lung tumor growth in vivo, decreased SPRY4 expression dramatically, and induced EGFR, AKT signaling activation, as well as epithelial–mesenchymal transition (EMT) simultaneously in tumor tissues. In addition, we showed that miR-411-5p also targeted tumor suppressor TXNIP, involved in regulating positively cell cycle progress in SPC-A1 cells rather than in H1299. Whether cell specificity of low TXNIP mRNA level in H1299 is responsible for the different response to cell cycle between H1299 and SPC-A1 would need further explorations. Collectively, these results suggest that miR-411-5p/3p are required for NSCLC development by suppressing SPRY4 and TXNIP; thus, the miR-411-SPRY4-AKT axis might act as a promising target for lung cancer therapy clinically.

Heme oxygenase-1 protects airway epithelium against apoptosis by targeting the proinflammatory NLRP3-RXR axis in asthma

Asthma is thought to be caused by malfunction of type 2 T helper cell (Th2)-mediated immunity, causing excessive inflammation, mucus overproduction, and apoptosis of airway epithelial cells. Heme oxygenase-1 (HO-1) functions in heme catabolism and is both cytoprotective and anti-inflammatory. We hypothesized that this dual function may be related to asthma's etiology. Using primary airway epithelial cells (pAECs) and an asthma mouse model, we demonstrate that severe lung inflammation is associated with rapid pAEC apoptosis. Surprisingly, NOD-like receptor protein 3 (NLRP3) inhibition, retinoid X receptor (RXR) deficiency, and HO-1 induction were associated with abrogated apoptosis. MCC950, a selective small-molecule inhibitor of canonical and noncanonical NLRP3 activation, reduced RXR expression, leading to decreased pAEC apoptosis that was reversed by the RXR agonist adapalene. Of note, HO-1 induction in a mouse model of ovalbumin-induced eosinophilic asthma suppressed Th2 responses and reduced apoptosis of pulmonary pAECs. In vitro, HO-1 induction desensitized cultured pAECs to ovalbumin-induced apoptosis, confirming the in vivo observations. Critically, the HO-1 products carbon monoxide and bilirubin suppressed the NLRP3-RXR axis in pAECs. Furthermore, HO-1 impaired production of NLRP3-RXR-induced cytokines (interleukin [IL]-25, IL-33, thymic stromal lymphopoietin, and granulocyte-macrophage colony-stimulating factor) in pAECs and lungs. Finally, we demonstrate that HO-1 binds to the NACHT domain of NLRP3 and the RXRα and RXRβ subunits and that this binding is not reversed by Sn-protoporphyrin. Our findings indicate that HO-1 and its products are essential for pAEC survival to maintain airway epithelium homeostasis during NLRP3-RXR-mediated apoptosis and inflammation.

Gasotransmitters and the immune system: Mode of action and novel therapeutic targets

Gasotransmitters are a group of gaseous molecules, with pleiotropic biological functions. These molecules include nitric oxide (NO), hydrogen sulfide (H₂S), and carbon monoxide (CO). Abnormal production and metabolism of these molecules have been observed in several pathological conditions. The understanding of the role of gasotransmitters in the immune system has grown significantly in the past years, and independent studies have shed light on the effect of exogenous and endogenous gasotransmitters on immune responses. Moreover, encouraging results come from the efficacy of NO-, CO- and H₂S -donors in preclinical animal models of autoimmune, acute and chronic inflammatory diseases. To date, data on the influence of gasotransmitters in immunity and immunopathology are often scattered and partial, and the scarcity of clinical trials using NO-, CO- and H₂S -donors, reveals that more effort is warranted. This review focuses on the role of gasotransmitters in the immune system and covers the evidences on the possible use of gasotransmitters for the treatment of inflammatory conditions.

Fisetin administration improves LPS-induced acute otitis media in mouse in vivo

Acute otitis media is one of the most common infectious diseases worldwide in spite of the widespread vaccination. The present study was conducted to explore the effects of fisetin on mouse acute otitis media models. The animal models were established by lipopolysaccharide (LPS) injection into the middle ear of mice via the tympanic membrane. Fisetin was administered to mice for ten days through intragastric administration immediate after LPS application. Hematoxylin and eosin (H&E) staining was performed and the pro-inflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-6 and VEGF, were measured through enzyme-linked immunosorbent assay (ELISA) method and RT-qPCR analysis. Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway was detected by immunoblotting assays. Reactive oxygen species (ROS) generated levels were determined through assessment of anti-oxidants, and TXNIP/MAPKs signaling pathways were explored to reveal the possible molecular mechanism for acute otitis media progression and the function of fisetin. Fisetin reduced mucosal thickness caused by LPS. In fisetin-treated animals, pro-inflammatory cytokine release was downregulated accompanied with TLR4/NF-κB inactivation. ROS production was significantly decreased in comparison to the LPS-treated group. The TXNIP/MAPKs signaling pathway was inactivated for fisetin treatment in LPS-induced mice with acute otitis media. The above results indicated that fisetin improved acute otitis media through inflammation and ROS suppression via inactivating TLR4/NF-κB and TXNIP/MAPKs signaling pathways.

Carbon monoxide releasing molecule‑3 promotes the osteogenic differentiation of rat bone marrow mesenchymal stem cells by releasing carbon monoxide

Stem cell‑based therapies are promising strategies to stimulate bone regeneration. Carbon monoxide releasing molecule‑3 (CORM‑3) exhibits multiple regulatory effects in a number of cells by releasing carbon monoxide (CO). The present study aimed to investigate the influence of CORM‑3 on the osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs). BMSCs were divided into five groups: A CORM‑3‑osteogenic group, in which cells were pretreated with CORM‑3 and subjected to osteogenic differentiation induction using osteogenic medium; an osteogenic group, in which cells were cultured in osteogenic medium; a degassed CORM‑3‑osteogenic group, in which cells were pretreated with degassed CORM‑3 and subjected to osteogenic differentiation induction; a CORM‑3 group, in which cells were cultured in control medium containing CORM‑3; and a control group, in which cells were cultured in control medium alone. The osteo‑specific mRNA and protein expression of runt‑related transcription factor 2 (Runx2), osteocalcin (OCN) and osteopontin (OPN) were assessed using reverse transcription‑quantitative polymerase chain reaction and western blot analysis. Alkaline phosphatase (ALP) activity was also examined and mineralization was detected using alizarin red staining. Levels of Runx2, OCN and OPN mRNA and protein in the CORM‑3‑osteogenic group were significantly increased compared with the osteogenic group (P<0.05), with the exception of OCN protein levels on day 3. The mRNA and protein expression of Runx2, OCN and OPN in the degassed CORM‑3‑osteogenic and osteogenic groups were similar. In addition, the mRNA and protein expression of Runx2, OCN and OPN in the CORM‑3 and control group were similar. ALP activity in the CORM‑3‑osteogenic group was increased from day 3 and remained significantly higher compared with all other groups on days 3, 5 and 7 (P<0.05). Additionally, the results indicated that the optical density value of alizarin red staining in the CORM‑3‑osteogenic group was significantly increased compared with the other groups (P<0.05). Therefore, the present study demonstrated that CORM‑3 may promote the osteogenic differentiation of BMSCs by releasing CO.

Lung Diseases

Inflammasomes are large innate cytoplasmic complexes that play a major role in promoting inflammation in the lung in response to a range of environmental and infectious stimuli. Inflammasomes are critical for driving acute innate immune responses that resolve infection and maintain tissue homeostasis. However, dysregulated or excessive inflammasome activation can be detrimental. Here, we discuss the plethora of recent data from clinical studies and small animal disease models that implicate excessive inflammasome responses in the pathogenesis of a number of acute and chronic respiratory inflammatory diseases. Understanding of the role of inflammasomes in lung disease is of great therapeutic interest.