The NLRP3 inflammasome: role in airway inflammation

Targeting PGAM5 attenuates airway inflammation in asthma by inhibiting HMGB1 release in bronchial epithelium

Previous studies have demonstrated that high-mobility group box protein 1(HMGB1) was increased and released to the extracellular and participated in the pathogenesis of steroid-insensitive asthma induced by toluene diisocyanate (TDI). Mitochondrial dysfunction of bronchial epithelia is a critical feature in TDI asthma. However, whether mitochondrial dysfunction regulated HMGB1 release in asthma remains unknown. The aim of this study was to explore whether phosphoglycerate mutase family member 5 (PGAM5), a mitochondrial protein, can regulate HMGB1 release in TDI-induced asthma. The gene expression data series (GSE) 67472 from gene expression omnibus (GEO) database was analyzed to compare the levels of PGAM5 in airway epithelial cells from asthma patients and healthy individuals. Male C57BL/6J mice were sensitized and challenged with TDI and treated with the PGAM5 inhibitor LFHP-1c. In vitro, human bronchial epithelial cells(16HBE) were stimulated by TDI-human serum albumin (HSA) and pretreated with PGAM5 siRNA. In this study, we observed PGAM5 expression was notably increased in airway epithelial cells of asthma patients and TDI-induced asthma mice. In vivo, inhibition of PGAM5 significantly ameliorated airway inflammation, airway hyperresponsiveness (AHR) and mucus hypersecretion, coupled with the decrease of pulmonary HMGB1 expression and release in TDI-exposed mice. In vitro, inhibition of PGAM5 improved mitochondrial dysfunction, decreased the production of reactive oxygen species (ROS) in mitochondrial. Knockdown of PGAM5 reduced the release of cytochrome C (cyt c) and HMGB1 release in TDI-induced asthma. Mechanistically, PGAM5 in bronchial epithelial cells treated by TDI-HSA significantly increased the dephosphorylation of Bax at the S184 residue, promoted the translocation of Bax to mitochondria, and contributed to the activation of mitochondrial-dependent apoptosis in TDI-induced asthma. Based on these findings, we uncovered a novel regulatory mechanism by which high PGAM5 expression promotes airway inflammation by mediating HMGB1 release in TDI-induced asthma, identifying the therapeutic effects of targeting PGAM5 in steroid-insensitive asthma model.

Protective effects of pioglitazone in renal ischemia-reperfusion injury (RIRI): focus on oxidative stress and inflammation

BACKGROUND

Renal ischemia-reperfusion injury (RIRI) is a critical phenomenon that compromises renal function and is the most serious health concern related to acute kidney injury (AKI). Pioglitazone (Pio) is a known agonist of peroxisome proliferator-activated receptor-gamma (PPAR-γ). PPAR-γ is a nuclear receptor that regulates genes involved in inflammation, metabolism, and cellular differentiation. Activation of PPAR-γ is associated with antiinflammatory and antioxidant effects, which are relevant to the pathophysiology of RIRI. This study aimed to investigate the protective effects of Pio in RIRI, focusing on oxidative stress and inflammation.

METHODS

We conducted a comprehensive literature search using electronic databases, including PubMed, ScienceDirect, Web of Science, Scopus, and Google Scholar.

RESULTS

The results of this study demonstrated that Pio has antioxidant, anti-inflammatory, and anti-apoptotic activities that counteract the consequences of RIRI. The study also discussed the underlying mechanisms, including the modulation of various pathways such as TNF-α, NF-κB signaling systems, STAT3 pathway, KIM-1 and NGAL pathways, AMPK phosphorylation, and autophagy flux. Additionally, the study presented a summary of various animal studies that support the potential protective effects of Pio in RIRI.

CONCLUSION

Our findings suggest that Pio could protect the kidneys from RIRI by improving antioxidant capacity and decreasing inflammation. Therefore, these findings support the potential of Pio as a therapeutic strategy for preventing RIRI in different clinical conditions.

Airway IL-1β is related to disease severity and mucociliary function in bronchiectasis

RATIONALE

The inflammasome is a key regulatory complex of the inflammatory response leading to interleukin-1β (IL-1β) release and activation. IL-1β amplifies inflammatory responses and induces mucus secretion and hyperconcentration in other diseases. The role of IL-1β in bronchiectasis has not been investigated.

OBJECTIVES

To characterise the role of airway IL-1β in bronchiectasis, including the association with mucus properties, ciliary function, airway inflammation, microbiome and disease severity.

METHODS

Stable bronchiectasis patients were enrolled in an international cohort study (n=269). IL-1β was measured in sputum supernatant. A validation cohort also had sputum rheology and hydration measured (n=53). For analysis, patients were stratified according to the median value of IL-1β in the population (high versus low) to compare disease severity, airway infection, microbiome (16S rRNA sequencing), inflammation and caspase-1 activity. Primary human nasal epithelial cells grown in air-liquid interface culture were used to study the effect of IL-1β on cilia function.

RESULTS

Patients with high sputum IL-1β had more severe disease, increased caspase-1 activity and an increased T-helper type 1, T-helper type 2 and neutrophil inflammatory response compared with patients with low IL-1β. The active-dominant form of IL-1β was associated with increased disease severity. High IL-1β was related to higher relative abundance of Proteobacteria in the microbiome and increased mucus solid content and viscoelastic properties. Chronic IL-1β treatment reduced the functionality of cilia and tight junctions of epithelial cells in vitro.

CONCLUSIONS

A subset of stable bronchiectasis patients show increased airway IL-1β, suggesting pulmonary inflammasome activation is linked with more severe disease, airway infection, mucus dehydration and epithelial dysfunction.

Association of Novel Antihyperglycemic Drugs Versus Metformin With a Decrease in Asthma Exacerbations

BACKGROUND

Similar to metformin, dipeptidyl peptidase-4 inhibitors (DPP-4 Is), glucagon-like peptidase 1 receptor agonists (GLP-1 RAs), and sodium glucose co-transporter-2 inhibitors (SGLT-2 Is) may improve control of asthma owing to their multiple potential mechanisms, including differential improvements in glycemic control, direct anti-inflammatory effects, and systemic changes in metabolism.

OBJECTIVE

To investigate whether these novel antihyperglycemic drugs were associated with fewer asthma exacerbations compared with metformin in patients with asthma comorbid with type 2 diabetes.

METHODS

Using a Japanese national administrative database, we constructed 3 active comparators-new user cohorts of 137,173 patients with a history of asthma starting the novel antihyperglycemic drugs and metformin between 2014 and 2022. Patient characteristics were balanced using overlap propensity score weighting. The primary outcome was the first exacerbation requiring systemic corticosteroids, and the secondary outcomes included the number of exacerbations requiring systemic corticosteroids.

RESULTS

DPP-4 Is and GLP-1 RAs were associated with a higher incidence of exacerbations requiring systemic corticosteroids compared with metformin (DPP-4 Is: 18.2 vs 17.4 per 100 person-years, hazard ratio: 1.09, 95% confidence interval [CI]: 1.05-1.14; GLP-1 RAs: 24.9 vs 19.0 per 100 person-years, hazard ratio: 1.14, 95% CI: 1.01-1.28). In contrast, the incidence of exacerbations requiring systemic corticosteroids was similar between the SGLT-2 Is and metformin groups (17.3 vs 18.1 per 100 person-years, hazard ratio: 1.00, 95% CI: 0.97-1.03). While DPP-4 Is and GLP-1 RAs were associated with more exacerbations requiring systemic corticosteroids, SGLT-2 Is were associated with slightly fewer exacerbations requiring systemic corticosteroids (53.7 vs 56.6 per 100 person-years, rate ratio: 0.95, 95% CI: 0.91-0.99).

CONCLUSIONS

While DPP-4 Is and GLP-1 RAs were associated with poorer control of asthma compared with metformin, SGLT-2 Is offered asthma control comparable to that of metformin.

Penicilazaphilone C alleviates allergic airway inflammation and improves the immune microenvironment by hindering the NLRP3 inflammasome

AIMS

Penicilazaphilone C (PAC) is hypothesized to potentially serve as a therapeutic treatment for allergic airway inflammation by inhibiting the NLRP3 inflammasome and reducing oxidative stress.

METHODS

An allergic asthma model was induced in female BALB/c mice of the OVA, OVA+PAC, OVA+PAC+LPS, and OVA+Dex groups by sensitizing and subsequently challenging them with OVA. The OVA+PAC and Normal+PAC groups were treated with PAC, while the OVA+PAC+LPS group also received LPS. The OVA+Dex group was given dexamethasone (Dex). Samples of serum, bronchoalveolar lavage fluid (BALF), and lung tissue were collected for histological and cytological analysis.

RESULTS

Allergic mice treated with PAC or Dex showed inhibited inflammation and mucus production in the lungs. There was a decrease in the number of inflammatory cells in the BALF, lower levels of inflammatory cytokines in the serum and BALF, and a reduction in the protein expression of NLRP3, ASC, cleaved caspase-1, IL-1β, activated gasdermin D, MPO, Ly6G, and ICAM-1. Additionally, oxidative stress was reduced, as shown by a decrease in MDA and DCF, but an increase in SOD and GSH. Treatment with PAC also resulted in a decrease in pulmonary memory CD4+ T cells and an increase in regulatory T cells. However, the positive effects seen in the PAC-treated mice were reversed when the NLRP3 inflammasome was activated by LPS, almost returning to the levels of the Sham-treated mice.

SIGNIFICANCE

PAC acts in a similar way to anti-allergic inflammation as Dex, suggesting it may be a viable therapeutic option for managing allergic asthma inflammation.

The Interaction of OTUB1 and TRAF3 Mediates NLRP3 Inflammasome Activity to Regulate TGF-β1-induced BEAS-2B Cell Injury

Asthma is a frequently chronic respiratory disease with inflammation and remodeling in the airway. OTUB1 has been reported to be associated with pulmonary diseases. However, the role and potential mechanism of OTUB1 in asthma remain unclear. The expressions of OTUB1 in the bronchial mucosal tissues of asthmatic children and TGF-β1-induced BEAS-2B cells were determined. The biological behaviors were assessed in an asthma in vitro model using a loss-function approach. The contents of inflammatory cytokines were detected by ELISA kits. The related protein expressions were performed using western blot assay. Besides, the interaction between OTUB1 and TRAF3 was detected by Co-IP and ubiquitination assays. Our results showed that OTUB1 level was increased in asthmatic bronchial mucosal tissues and TGF-β1-induced BEAS-2B cells. OTUB1 knockdown promoted proliferation, inhibited apoptosis and EMT of TGF-β1-treated cells. The inhibition of OTUB1 attenuated the TGF-β1-induced inflammation and remodeling. Furthermore, OTUB1 knockdown inhibited the deubiquitination of TRAF3 and further suppressed the activation of NLRP3 inflammasome. The overexpression of TRAF3 or NLRP3 reversed the positive role of OTUB1 knockdown in TGF-β1-induced cells injury. Collectively, OTUB1 deubiquitinates TRAF3 to activate NLRP3 inflammasome, thereby leading to inflammation and remodeling of TGF-β1-induced cells, and further promoting the pathogenesis of asthma.

Exploring the role of COX-2 in Alzheimer's disease: Potential therapeutic implications of COX-2 inhibitors

This review highlights the potential role of cyclooxygenase-2 enzyme (COX-2) in the pathogenesis of Alzheimer's disease (AD) and the potential therapeutic use of non-steroidal anti-inflammatory drugs (NSAIDs) in the management of AD. In addition to COX-2 enzymes role in inflammation, the formation of amyloid plaques and neurofibrillary tangles in the brain, the review emphasizes that COXs-2 have a crucial role in normal synaptic activity and plasticity, and have a relationship with acetylcholine, tau protein, and beta-amyloid (Aβ) which are the main causes of Alzheimer's disease. Furthermore, the review points out that COX-2 enzymes have a relationship with kinase enzymes, including Cyclin Dependent Kinase 5 (CDK5) and Glycogen Synthase Kinase 3β (GSK3β), which are known to play a role in tau phosphorylation and are strongly associated with Alzheimer's disease. Therefore, the use of drugs like NSAIDs may be a hopeful approach for managing AD. However, results from studies examining the effectiveness of NSAIDs in treating AD have been mixed and further research is needed to fully understand the mechanisms by which COX-2 and NSAIDs may be involved in the development and progression of AD and to identify new therapeutic strategies.

Phenotype overlap in the natural history of asthma

The heterogeneity of asthma makes it challenging to unravel the pathophysiologic mechanisms of the disease. Despite the wealth of research identifying diverse phenotypes, many gaps still remain in our knowledge of the disease's complexity. A crucial aspect is the impact of airborne factors over a lifetime, which often results in a complex overlap of phenotypes associated with type 2 (T2), non-T2 and mixed inflammation. Evidence now shows overlaps between the phenotypes associated with T2, non-T2 and mixed T2/non-T2 inflammation. These interconnections could be induced by different determinants such as recurrent infections, environmental factors, T-helper plasticity and comorbidities, collectively resulting in a complex network of distinct pathways generally considered as mutually exclusive. In this scenario, we need to abandon the concept of asthma as a disease characterised by distinct traits grouped into static segregated categories. It is now evident that there are multiple interplays between the various physiologic, cellular and molecular features of asthma, and the overlap of phenotypes cannot be ignored.

NLRP3 Inflammasome as a Potential Therapeutic Target in Dry Eye Disease

Dry eye disease (DED) is a multifactorial ocular surface disorder arising from numerous interrelated underlying pathologies that trigger a self-perpetuating cycle of instability, hyperosmolarity, and ocular surface damage. Associated ocular discomfort and visual disturbance contribute negatively to quality of life. Ocular surface inflammation has been increasingly recognised as playing a key role in the pathophysiology of chronic DED. Current readily available anti-inflammatory agents successfully relieve symptoms, but often without addressing the underlying pathophysiological mechanism. The NOD-like receptor protein-3 (NLRP3) inflammasome pathway has recently been implicated as a key driver of ocular surface inflammation, as reported in pre-clinical and clinical studies of DED. This review discusses the intimate relationship between DED and inflammation, highlights the involvement of the inflammasome in the development of DED, describes existing anti-inflammatory therapies and their limitations, and evaluates the potential of the inflammasome in the context of the existing anti-inflammatory therapeutic landscape as a therapeutic target for effective treatment of the disease.

Mycoplasma pneumoniae – modern data on the structure, molecular biology and epidemiology of the pathogen

Mycoplasma pneumoniae is a common etiologic agent of respiratory tract infections and community-acquired pneumonia (CAP) in children and adults. Recently, much new data on this pathogen, its molecular biology, cytoadherence and epidemiology have been accumulated. This review describes in detail the features of the microorganism and the pathogenesis of the diseases caused, clinical manifestations, provides data on the epidemiology of the incidence of respiratory mycoplasmosis and CAP caused by this microorganism in the world, discusses the issues of asymptomatic carriage, considers the problems of laboratory diagnosis, antibiotic therapy and antibiotic resistance of the pathogen.

Hesperetin from Root Extract of Clerodendrum petasites S. Moore Inhibits SARS-CoV-2 Spike Protein S1 Subunit-Induced NLRP3 Inflammasome in A549 Lung Cells via Modulation of the Akt/MAPK/AP-1 Pathway

Inhibition of inflammatory responses from the spike glycoprotein of SARS-CoV-2 (Spike) by targeting NLRP3 inflammasome has recently been developed as an alternative form of supportive therapy besides the traditional anti-viral approaches. Clerodendrum petasites S. Moore (C. petasites) is a Thai traditional medicinal plant possessing antipyretic and anti-inflammatory activities. In this study, C. petasites ethanolic root extract (CpEE) underwent solvent-partitioned extraction to obtain the ethyl acetate fraction of C. petasites (CpEA). Subsequently, C. petasites extracts were determined for the flavonoid contents and anti-inflammatory properties against spike induction in the A549 lung cells. According to the HPLC results, CpEA significantly contained higher amounts of hesperidin and hesperetin flavonoids than CpEE (p < 0.05). A549 cells were then pre-treated with either C. petasites extracts or its active flavonoids and were primed with 100 ng/mL of spike S1 subunit (Spike S1) and determined for the anti-inflammatory properties. The results indicate that CpEA (compared with CpEE) and hesperetin (compared with hesperidin) exhibited greater anti-inflammatory properties upon Spike S1 induction through a significant reduction in IL-6, IL-1β, and IL-18 cytokine releases in A549 cells culture supernatant (p < 0.05). Additionally, CpEA and hesperetin significantly inhibited the Spike S1-induced inflammatory gene expressions (NLRP3, IL-1β, and IL-18, p < 0.05). Mechanistically, CpEA and hesperetin attenuated inflammasome machinery protein expressions (NLRP3, ASC, and Caspase-1), as well as inactivated the Akt/MAPK/AP-1 pathway. Overall, our findings could provide scientific-based evidence to support the use of C. petasites and hesperetin in the development of supportive therapies for the prevention of COVID-19-related chronic inflammation.

Low tidal volume ventilation alleviates ventilator-induced lung injury by regulating the NLRP3 inflammasome

PURPOSE

Low tidal volume ventilation (LTVV) is a well-known ventilation mode which can improve ventilator-induced lung injury (VILI). However, the mechanism of LTVV ameliorating VILI has not yet been elucidated. In this study, we aimed to reveal LTVV protected against VILI by inhibiting the activation of the NLRP3 inflammasome in bronchoalveolar lavage fluid (BALF) from humans and lungs from mice.

MATERIALS AND METHODS

Twenty-eight patients scheduled for video-assisted thoracoscopic esophagectomy were randomized to receive high-tidal-volume ventilation [V_t = 10 mL/kg without positive end-expiratory pressure (PEEP)] or LTVV (V_t = 5 mL/kg along with 5 cm of H₂O PEEP) during one-lung ventilation. BALF was collected before and at the end of surgery. Male C57BL/6 mice received high-tidal-volume ventilation, LTVV or MCC950 (an inhibitor of NLRP3). The activation of the formation of NLRP3 inflammasome in BALF from patients and in lungs from mice were analyzed.

RESULTS

LTTV decreased the peak airway pressure (P_peak), plateau airway pressure (P_plat) and driving pressure (ΔP) during one-lung ventilation. Additionally, LTVV not only inhibited pulmonary infiltration and inflammation caused by mechanical ventilation, but also suppressed the NLRP3 inflammasome activation in BALF from humans. In mice, ventilator-induced inflammatory response and pulmonary edema were suppressed by LTVV with an efficacy comparable to that of MCC950 treatment. Furthermore, LTVV, similar to MCC950, clearly decreased ventilator-induced NLRP3 inflammasome activation.

CONCLUSION

Our study showed that LTVV played a protective role in ventilator-induced lung injury by suppressing the activation of the NLRP3 inflammasome.

TRIAL REGISTRATION

This study was registered in The Chinese Clinical Trial Registry, ChiCTR1900026190 on 25 September 2019.

Mesoporous sodium four-coordinate aluminosilicate nanoparticles modulate dendritic cell pyroptosis and activate innate and adaptive immunity

Pyroptosis is a programmed cell death widely studied in cancer cells for tumour inhibition, but rarely in dendritic cell (DC) activation for vaccine development. Here, we report the synthesis of sodium stabilized mesoporous aluminosilicate nanoparticles as DC pyroptosis modulators and antigen carriers. By surface modification of sodium-stabilized four-coordinate aluminium species on dendritic mesoporous silica nanoparticles, the resultant Na-IVAl-DMSN significantly activated DC through caspase-1 dependent pyroptosis via pH responsive intracellular ion exchange. The released proinflammatory cellular contents further mediated DC hyperactivation with prolonged cytokine release. In vivo studies showed that Na-IVAl-DMSN induced enhanced cellular immunity mediated by natural killer (NK) cells, cytotoxic T cells, and memory T cells as well as humoral immune response. Our results provide a new principle for the design of next-generation nanoadjuvants for vaccine applications.

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.

IL-35 inhibits cell pyroptosis and attenuates cell injury in TNF-α-induced bronchial epithelial cells via p38 MAPK signaling pathway

Asthma is a chronic inflammatory disease of the airways, and IL-35 has been found to be involved in the pathogenesis of inflammatory diseases by mediating the inhibition of effector T cells. But the role of IL-35 on cell pyroptosis, which frequently occurs in inflammatory diseases, has not been elucidated. Therefore, the present study used a TNF-α-induced bronchial epithelial cell injury model to investigate the mechanism of IL-35 action on cell pyroptosis and asthma injury. The effects of IL-35 on cell activity, inflammatory factor levels, cell barrier damage and cell pyroptosis-related proteins were examined by CCK-8, ELISA, lucifer yellow permeability and Western blotting assay, respectively. Subsequently, following the activation of p38 MAPK signaling pathway by adding p38 agonist, the effect of IL-35 on TNF-α-induced bronchial epithelial cell injury was investigated. The results showed that IL-35 reduced TNF-α-induced cell injury, decreased inflammatory factors, improved cell permeability, and inhibited cell pyroptosis. More importantly, the effect of IL-35 on injured cells was reversed after p38 MAPK pathway was activated. In summary, IL-35 inhibited p38 MAPK pathway to suppress cell pyroptosis and thereby reduce asthma injury.

Chlorogenic acid ameliorates Klebsiella pneumoniae-induced pneumonia in immunosuppressed mice via inhibiting the activation of NLRP3 inflammasomes

Chlorogenic acid (CGA) possesses a wide variety of bioactive properties, such as antioxidation, anti-inflammation and anti-bacteria. This study was aimed at exploring the effects of CGA of anti-inflammation and anti-bacteria on mouse pneumonia prepared by immunosuppressed mice infected with Klebsiella pneumoniae (K. pneumoniae) in vivo and the cellular inflammasomes through lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced RAW 264.7 murine macrophages in vitro. Mice received CGA treatment (30 and 90 mg kg^-1) for 8 consecutive days and on the fourth day immunosuppression in mice was induced by cyclophosphamide (40 mg kg^-1) for 5 days before inoculation of K. pneumoniae. Immunosuppressed mice infected with K. pneumoniae developed severe pneumonia, with marked interstitial vascular congestion, widened alveolar intervals, infiltration of monocytes, lymphocytes and macrophages as well as the damage of epithelial architecture, with growing mortality and count forming unit (CFU). CGA treatment significantly decreased the ratio of lung/body weight, reduced the severity of pneumonia induced by K. pneumoniae, decreased the lung injury, inflammatory cell infiltration scores and CD68 protein expression, inhibited the expression of interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, and elevated the expression of IL-10. Meanwhile, we investigated the mechanism of CGA to counter K. pneumoniae-induced pneumonia and found that CGA remarkably repressed the activation of nucleotide-binding domain like receptor protein 3 (NLRP3) inflammasome. Altogether, our results indicate that the dietary intake of CGA or its rich foods ameliorates K. pneumonia-induced pneumonia by inhibiting the activation of NLRP3 inflammasomes.

Inhibition of the Inflammasome Activity of NLRP3 Attenuates HDM-Induced Allergic Asthma

Inhaled allergens promote inflammatory response, tissue damage, and airway hyperresponsiveness in the lungs, leading to allergic asthma. NLRP3, as an immune sensor of infections and cellular stress, is associated with the development and exacerbation of asthma. However, the mechanism by which NLRP3 affects asthma requires further investigation. Here, we showed that inhaled house dust mite (HDM) promotes NLRP3 inflammasome activation in the lungs and specifically induces the maturation of caspase-1 and IL-1β in alveolar macrophages (AMs). Using Nlrp3-mutant mice, we found that NLRP3 promotes the inflammatory response and pathogenesis in HDM-induced allergic asthma in an inflammasome-dependent manner. Treatment with RRx-001, an NLRP3 inhibitor, significantly reduced inflammatory cell infiltration and mucus secretion in the airway. Our results showed that NLRP3 in myeloid cells promoted the development and progression of allergic asthma in an inflammasome-dependent manner. Small molecules targeting the NLRP3 inflammasome may provide new treatment options for this disease.

Possible Beneficial Actions of Caffeine in SARS-CoV-2

The COVID-19 pandemic has established an unparalleled necessity to rapidly find effective treatments for the illness; unfortunately, no specific treatment has been found yet. As this is a new emerging chaotic situation, already existing drugs have been suggested to ameliorate the infection of SARS-CoV-2. The consumption of caffeine has been suggested primarily because it improves exercise performance, reduces fatigue, and increases wakefulness and awareness. Caffeine has been proven to be an effective anti-inflammatory and immunomodulator. In airway smooth muscle, it has bronchodilator effects mainly due to its activity as a phosphodiesterase inhibitor and adenosine receptor antagonist. In addition, a recent published document has suggested the potential antiviral activity of this drug using in silico molecular dynamics and molecular docking; in this regard, caffeine might block the viral entrance into host cells by inhibiting the formation of a receptor-binding domain and the angiotensin-converting enzyme complex and, additionally, might reduce viral replication by the inhibition of the activity of 3-chymotrypsin-like proteases. Here, we discuss how caffeine through certain mechanisms of action could be beneficial in SARS-CoV-2. Nevertheless, further studies are required for validation through in vitro and in vivo models.

Inhibition of uric acid or IL-1β ameliorates respiratory syncytial virus immunopathology and development of asthma

BACKGROUND

Respiratory syncytial virus (RSV) affects most infants early in life and is associated with increased asthma risk. The specific mechanism remains unknown.

OBJECTIVE

To investigate the role of uric acid (UA) and IL-1β in RSV immunopathology and asthma predisposition.

METHODS

Tracheal aspirates from human infants with and without RSV were collected and analyzed for pro-IL-1β mRNA and protein to establish a correlation in human disease. Neonatal mouse models of RSV were employed, wherein mice infected at 6-7 days of life were analyzed at 8 days postinfection, 5 weeks postinfection, or after a chronic cockroach allergen asthma model. A xanthine oxidase inhibitor or IL-1 receptor antagonist was administered during RSV infection.

RESULTS

Human tracheal aspirates from RSV-infected infants showed elevated pro-IL-1β mRNA and protein. Inhibition of UA or IL-1β during neonatal murine RSV infection decreased mucus production, reduced cellular infiltrates to the lung (especially ILC2s), and decreased type 2 immune responses. Inhibition of either UA or IL-1β during RSV infection led to chronic reductions in pulmonary immune cell composition and reduced type 2 immune responses and reduced similar responses after challenge with cockroach antigen.

CONCLUSIONS

Inhibiting UA and IL-1β during RSV infection ameliorates RSV immunopathology, reduces the consequences of allergen-induced asthma, and presents new therapeutic targets to reduce early-life viral-induced asthma development.

Chrysin-loaded PLGA attenuates OVA-induced allergic asthma by modulating TLR/NF-κB/NLRP3 axis

Asthma, one of the significant public health problems, is triggered by certain inflammatory processes in the airways that are not addressed propitiously by current therapies. Though pieces of evidence on allergic asthma mitigation by the anti-inflammatory bioflavonoid chrysin (CHR) are accumulating, poor bioavailability, and low solubility curtail drug development. To overcome these shortcomings, CHR loaded nanoparticle (CHR-NP) was formulated, and its salutary effect in preclinical murine allergic asthma model via the peroral route was evaluated. The spherical nanosized particles showed slow, sustained release in vitro. Moreover, CHR-NP dramatically reduced the serum IgE, ovalbumin (OVA)-induced lung histological alteration, as well as Th2 (T-helper 2) cytokines in the bronchoalveolar lavage fluid (BALF). It also suppressed the elevated serum pro-inflammatory cytokines and their upstream TLR/NF-κB/NLRP3 pathway activation in lung superior to CHR and almost identical to dexamethasone (DEX). Thus this study suggests the potentiality of CHR-NP in ameliorating allergic asthma progression.

TLR9 mediates the activation of NLRP3 inflammasome and oxidative stress in murine allergic airway inflammation

Toll-like receptor 9 (TLR9) has been reported to mediate airway inflammation, however, the underlying mechanism is poorly understood. In the present study, our objective was to reveal whether TLR9 regulates NLRP3 inflammasome and oxidative stress in murine allergic airway inflammation and Raw264.7 cells. Female wild type(WT)and TLR9^-/-mice on C57BL/6 background were used to induce allergic airway inflammation by challenge of OVA, and Raw264.7 cells with or without TLR9 knockdown by small interfering RNA (siRNA) were stimulated by S.aureus. The results demonstrated that deletion of TLR9 effectively attenuated OVA-induced allergic airway inflammation including inflammatory cells infiltration and goblet cell hyperplasia. Meanwhile, OVA-induced protein expression of NLRP3, caspase-1(p20) and mature IL-1β, as well as secretion of IL-1β and IL-18 in wild type mice (WT) was obviously suppressed by TLR9 deficiency. Concomitantly, the expression of oxidative markers 8-OhDG and nitrotyrosine was increased in OVA-challenged WT mice, while TLR9 deficiency significantly inhibited such increase. Similarly, in the in vitro study, we found that knockdown of TLR9 markedly suppressed S.aureus-induced activation of NLRP3 inflammasome and oxidative stress in Raw264.7 cells. Collectively, our findings indicated that TLR9 may mediate allergic airway inflammation via activating NLRP3 inflammasome and oxidative stress.

Silica dioxide nanoparticles aggravate airway inflammation in an asthmatic mouse model via NLRP3 inflammasome activation

Silica dioxide nanoparticles (SiONPs) are mainly used in the rubber industry; however, they are a major air pollutant in Asia. Thus, extensive research on this issue is required. In this study, we investigated the effects of SiONPs on asthma aggravation and elucidated the underlying mechanism using ovalbumin (OVA)-induced asthmatic mice model and in NCI-H292 cells. Mice exposed to SiONPs showed markedly increased Penh values, inflammatory cell counts, and inflammatory cytokine levels compared to OVA-induced asthmatic mice. Exposure to SiONPs also induced additional airway inflammation and mucus secretion with increases in protein expression levels of thioredoxin-interacting protein (TXNIP), NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, and interleukin (IL)-1β compared to those in OVA-induced asthmatic mice. Treatment of SiONPs in NCI-H292 cells also significantly increased mRNA expression levels of inflammatory cytokines accompanied with elevation in the levels of TXNIP, NLRP3 inflammasome, and IL-1β proteins in a concentration-dependent manner. Taken together, exposure to SiONPs aggravated asthma development, which is closely related to inflammasome activation. Our results provide useful information about the toxicological effects of SiONPs on asthma exacerbation and suggest the need to avoid SiONP exposure especially in individuals with respiratory diseases.

Apolipoprotein E negatively regulates murine allergic airway inflammation via suppressing the activation of NLRP3 inflammasome and oxidative stress

Apolipoprotein E (ApoE) has been reported as a steroid unresponsive gene and functions as a negative regulator of airway hyperreactivity (AHR) and goblet cell hyperplasia in house dust mite (HDM)-challenged mice. However, the role of ApoE in Ovalbumin (OVA)-induced allergic airway inflammation disease and the underlying mechanism are still unknown. In the present study, murine allergic airway inflammation was induced by inhaled OVA for consecutive 7 days in wild type (WT) and ApoE^-/- mice. In the OVA-induced model, the ApoE level in the bronchoalveolar lavage fluid (BALF) and lung tissues was significantly higher than that of control mice. And ApoE deficiency aggravated airway inflammation including leukocytes infiltration, goblet cell hyperplasia and IgE production as compared to those of WT mice after OVA- challenged, suggesting ApoE servers as an endogenous negative regulator of airway inflammation. Furthermore, OVA challenge elevated the activation of NLRP3 inflammasome with higher protein expression of NLRP3, caspase1 and IL-1β, enhanced oxidative stress with higher expression of 8-OHdG, nitrotyrosine and SOD2, increased the expression of mitochondrial fusion/fission markers including Optic Atrophy 1 (OPA1), Mitofusion 2 (Mfn2), dynamin-related protein 1 (DRP1) and Fission 1 (Fis1). However, these OVA-induced changes were augmented in ApoE^-/- mice. Collectively, our results demonstrated that the OVA-induced airway inflammation was aggravated in ApoE^-/- mice, and suggested that the underlying mechanism may be associated with the augmented activation of NLRP3 inflammasome and oxidative stress in ApoE^-/- mice, therefore targeting ApoE pathway might be a novel therapy approach for allergic airway diseases such as asthma.

TLR2-Melatonin Feedback Loop Regulates the Activation of NLRP3 Inflammasome in Murine Allergic Airway Inflammation

Toll-like receptor 2 (TLR2) is suggested to initiate the activation of NLRP3 inflammasome, and considered to be involved in asthma. The findings that melatonin modulates TLRs-mediated immune responses, together with the suppressing effect of TLRs on endogenous melatonin synthesis, support the possibility that a feedback loop exists between TLRs system and endogenous melatonin synthesis. To determine whether TLR2-melatonin feedback loop exists in allergic airway disease and regulates NLRP3 inflammasome activity, wild-type (WT) and TLR2^−/− mice were challenged with OVA to establish allergic airway disease model. Following OVA challenge, WT mice exhibited increased-expression of TLR2, activation of NLRP3 inflammasome and marked airway inflammation, which were all effectively inhibited in the TLR2^−/− mice, indicating that TLR2-NLRP3 mediated airway inflammation. Meanwhile, melatonin biosynthesis was reduced in OVA-challenged WT mice, while such reduction was notably rescued by TLR2 deficiency, suggesting that TLR2-NLRP3-mediated allergic airway inflammation was associated with decreased endogenous melatonin biosynthesis. Furthermore, addition of melatonin to OVA-challenged WT mice pronouncedly ameliorated airway inflammation, decreased TLR2 expression and NLRP3 inflammasome activation, further implying that melatonin in turn inhibited airway inflammation via suppressing TLR2-NLRP3 signal. Most interestingly, although melatonin receptor antagonist luzindole significantly reduced the protein expressions of ASMT, AANAT and subsequent level of melatonin in OVA-challenged TLR2^−/− mice, it exhibited null effect on leukocytes infiltration, Th2-cytokines production and NLRP3 activity. These results indicate that a TLR2-melatonin feedback loop regulates NLRP3 inflammasome activity in allergic airway inflammation, and melatonin may be a promising therapeutic medicine for airway inflammatory diseases such as asthma.

Bronchial epithelial pyroptosis promotes airway inflammation in a murine model of toluene diisocyanate-induced asthma

Airway epithelial injury in response to allergens such as toluene diisocyanate (TDI) leads to persistent airway inflammation. Pyroptosis is recognized as a strong proinflammatory cell death process. However, the role of pyroptosis in bronchial epithelial injury and airway inflammation in TDI-induced asthma remains unknown. In this study, cytotoxic effect of TDI on 16HBE cells (a human bronchial epithelial cell line) was detected. Then a TDI-induced experimental asthma mouse model was established for in vivo study. Here we found that TDI induced pyroptosis in 16HBE cells, as evidenced by enhanced expressions of caspase-1 and elevated levels of LDH, IL-1β and HMGB1. As expected, TDI-induced inflammatory cell death was significantly blocked by a specific NLRP3 inflammasome inhibitor. Intriguingly, in asthmatic mice, the increased cleavages of caspase-1 and pyroptotic executioner gasdermin D (GSDMD) in bronchial epithelial cells were decreased by NLRP3 inflammasome inhibitor. Furthermore, inhibition of NLRP3 inflammasome attenuated airway hyper-responsiveness and airway inflammation, accompanied by lower levels of IL-1β, IgE and Th2-related cytokines. Our data suggest that bronchial epithelial pyroptosis exacerbates airway inflammation and hyper-responsiveness in TDI-induced asthma via NLRP3 inflammasome activation and GSDND cleavage. Therefore, NLRP3 inflammasome-mediated pyroptosis may be a potential treatment target for TDI-induced asthma.

Melatonin biosynthesis restored by CpG oligodeoxynucleotides attenuates allergic airway inflammation via regulating NLRP3 inflammasome

AIMS

Both CpG oligodeoxynucleotide (CpG-ODN) and melatonin have been reported to induce Th1 response and contribute to allergic asthma resistance. Here, we aimed to reveal how they confer such effect as well as whether they crosstalk with each other.

MAIN METHODS

Six-week-old Female C57BL/6 mice were challenged by OVA to induce allergic airway inflammation, and were treated with CpG-ODN, CpG-ODN plus Luzindole or melatonin respectively. Bronchoalveolar lavage fluid (BALF) cellularity was classified and counted by Wright's-Giemsa staining. HE and PAS staining were used to analyze airway inflammation. The levels of IL-4, IL-5, IL-13,GM-CSF and IFN-γ, as well as IL-1β and IL-18 were analyzed by ELISA. Protein expressions of ASMT, AANAT, NLRP3, IL-1β and caspase-1 in lung tissue were detected by Western blotting, expression of ASMT and AANAT were further observed by immunohistochemistry.

KEY FINDINGS

We found that CpG-ODN considerably suppressed OVA-induced airway leukocytes infiltration, goblet cell hyperplasia and Th2 cytokines production. Furthermore, the resolution effect of CpG-ODN on OVA-induced allergic airway inflammation occurred in parallel with decreased-activation of NLRP3 inflammasome and increased biosynthesis of melatonin. Blocking the effect of endogenous melatonin by Luzindole abolished the suppressive effect of CpG-ODN on OVA-induced airway inflammation and activation of NLRP3 inflammasome, suggesting such effect was mediated by endogenous melatonin. Moreover, exogenous melatonin pronouncedly ameliorated airway inflammation and decreased the activation of NLRP3 inflammasome.

SIGNIFICANCE

These results proven that CpG-ODN protects against allergic airway inflammation via suppressing the activation of NLRP3 inflammasome, and such effect may be resulted from the restored-production of melatonin.

Low-Dose Mitomycin C Decreases the Postoperative Recurrence Rate of Pterygium by Perturbing NLRP3 Inflammatory Signalling Pathway and Suppressing the Expression of Inflammatory Factors

A pterygium is generally believed to be a chronic inflammatory lesion caused by external stimuli that develops from the conjunctiva and grows onto the cornea. Simple bare sclera excision is the most commonly used method to treat pterygium. However, the high postoperative recurrence rate of pterygium remains a persistent challenge. Mitomycin C (MMC) is an antineoplastic antibiotic that inhibits DNA, RNA, and protein synthesis. In recent years, although MMC has proven useful for the treatment of pterygium, its application has been controversial because of its clear toxicity and the possibility of ocular complications. In the current study, we prospectively recruited patients to receive or not receive a local injection of MMC (0.4 mg/ml). Follow-up was conducted with the patients to determine the postoperative recurrence rate of pterygium and/or to observe any ocular complications. The remarkable results demonstrated that MMC can decrease the postoperative recurrence rate of pterygium without leading to serious eye complications. Further results indicated that MMC can inhibit the activation of the NLRP3 inflammatory signalling pathway and thus downregulate the expression of downstream molecules, including IL-18 and IL-1β. MMC also reduced the expression of inflammatory factors TGF-β1, VEGF, and IL-6. In addition to influencing these factors, MMC suppressed neovascularization and the proliferation of corneal fibroblasts to effectively reduce the recurrence rate of pterygium. Taken together, our results provide a theoretical basis for the development of prevention and treatment strategies for pterygium and suggest that MMC is highly effective as an adjunctive treatment after excision of primary pterygia.

Suhuang antitussive capsule inhibits NLRP3 inflammasome activation and ameliorates pulmonary dysfunction via suppression of endoplasmic reticulum stress in cough variant asthma

Pulmonary dysfunction is tightly associated with cough variant asthma (CVA), a respiratory damage disease. Suhuang antitussive capsule (Suhuang), one of traditional Chinese patent medicines, plays a crucial role in the treatment and complication of CVA in the long clinical application. In this study, we aimed to investigate the protective effects and underlying antitussive mechanisms of Suhuang on pulmonary function in ovalbumin (OVA)-induced CVA rats. Administration (i.g.) of Suhuang significantly alleviated pulmonary damage and dysfunction. Suhuang improved ER stress and PKCε translocation via regulation of Ca²⁺ trafficking. Suhuang also inhibited NLRP3 inflammasome activation, as evidenced by disrupting the assembly of NLRP3 inflammasome and reducing the expression of cleaved caspase-1, and decreased IL-1β secretion. Besides, it's identified that TXNIP induction and RIP1-RIP3-Drp1 pathway were required for the inhibitory routes of Suhuang from ER stress to NLRP3 inflammasome activation. Consistent with the in vivo findings, Suhuang also attenuated ER stress/NLRP3 inflammasome activation, and thereby restored pulmonary homeostasis in vitro. Meantime, these functions were diminished by blocking ER stress, indicating that ER stress is essential for the effects of Suhuang on pulmonary function. A further in vivo analysis showed that Suhuang-driven pharmacological inactivation of NLRP3 inflammasome and amelioration of pulmonary dysfunction were reversed by an ER stress inducer tunicamycin, well confirming the beneficial effects of Suhuang on pulmonary function by regulation of ER stress. Collectively, these results indicated that Suhuang contributed to impairing NLRP3 inflammasome activation via inhibition of ER stress, which was responsible for the protection of pulmonary homeostasis. These findings may provide a pharmacological groundwork and important new experimental data regarding the clinical treatment of Suhuang in CVA patients.

Associations of variants In the hexokinase 1 and interleukin 18 receptor regions with oxyhemoglobin saturation during sleep

Sleep disordered breathing (SDB)-related overnight hypoxemia is associated with cardiometabolic disease and other comorbidities. Understanding the genetic bases for variations in nocturnal hypoxemia may help understand mechanisms influencing oxygenation and SDB-related mortality. We conducted genome-wide association tests across 10 cohorts and 4 populations to identify genetic variants associated with three correlated measures of overnight oxyhemoglobin saturation: average and minimum oxyhemoglobin saturation during sleep and the percent of sleep with oxyhemoglobin saturation under 90%. The discovery sample consisted of 8,326 individuals. Variants with p < 1 × 10(-6) were analyzed in a replication group of 14,410 individuals. We identified 3 significantly associated regions, including 2 regions in multi-ethnic analyses (2q12, 10q22). SNPs in the 2q12 region associated with minimum SpO2 (rs78136548 p = 2.70 × 10(-10)). SNPs at 10q22 were associated with all three traits including average SpO2 (rs72805692 p = 4.58 × 10(-8)). SNPs in both regions were associated in over 20,000 individuals and are supported by prior associations or functional evidence. Four additional significant regions were detected in secondary sex-stratified and combined discovery and replication analyses, including a region overlapping Reelin, a known marker of respiratory complex neurons.These are the first genome-wide significant findings reported for oxyhemoglobin saturation during sleep, a phenotype of high clinical interest. Our replicated associations with HK1 and IL18R1 suggest that variants in inflammatory pathways, such as the biologically-plausible NLRP3 inflammasome, may contribute to nocturnal hypoxemia.

Inflammatory status and severity of disease in dengue patients are associated with lipoprotein alterations

INTRODUCTION

The triggering of severe dengue has been associated with an exacerbated inflammatory process characterized by the production of pro-inflammatory cytokines such as IL-1β/IL-18, which are the product of inflammasome activation. Furthermore, alteration in the levels of high-density (HDL) and low-density lipoproteins (LDL) has been observed; and HDL are known to have immunomodulatory properties, including the regulation of inflammasomes. While HDL would be expected to counteract hyperactivation of the inflammasome, the relationship between HDL and dengue severity, has not previously been explored.

METHODOLOGY

We conducted a cross-sectional study of 30 patients with dengue and 39 healthy controls matched by sex and age. Lipid profile and levels of C-reactive protein were quantified. Serum levels of IL-1β, IL-6, IL-10, IL-18, and TNF-α, were assessed by ELISA. Expression of inflammasome-related genes in PBMC was quantified by qPCR.

RESULTS

Dengue patients presented an alteration in the parameters of the lipid profile, with a significant decrease in HDL levels, which was more pronounced in dengue patients with warning signs. Moreover, a decrease in the expression of the inflammasome-related genes NLRP1, NLRC4, caspase-1, IL-1β and IL-18 was observed, as well as an increase in serum levels of C-reactive protein and IL-10 in dengue patients versus healthy donors. Significant positive correlations between LDL levels and the relative expression of NLRP3, NLRC4, IL-1β and IL-18, were found.

CONCLUSION

The results suggest that there is a relationship between the alteration of LDL and HDL with the imbalance in the inflammatory response, which could be associated with the severity of dengue.

NLRP3 deletion inhibits inflammation-driven mouse lung tumorigenesis induced by benzo(a)pyrene and lipopolysaccharide

Background

Inflammatory micro-environment has been proposed to play a critical role in lung tumorigenesis. NLRP3 is known as an intracellular receptor involving inflammation and has been reported which is increasingly associated with tumor development, but the role in inflammation-driven lung cancer has not been fully clarified. In this study, we investigated whether lipopolysaccharide (LPS)-induced pulmonary inflammation could contribute to lung tumorigenesis induced by benzo(a)pyrene [B(a)p] in C57BL/6J mice and the role of NLRP3 in the pathogenesis.

Methods

NLRP3−/− mice and C57BL/6J mice (wide-type, WT) were instilled intratracheally with B(a)p (1 mg/mouse) once a week for 4 times [the week of the last time of B(a)p treatment named Week 0], and mice were then instilled intratracheally with LPS at Week 3, 2.5 μg/mouse, once every three weeks for 5 times. At Week 30, the incidence, number, size and histopathology of lung tumor were analyzed.

Results

Mice exposed to B(a)p or B(a)p plus LPS could induce lung tumors, whereas LPS or vehicles treatment could not induce lung tumorigenesis. In WT mice, B(a)p plus LPS exposure significantly increased tumor incidence, mean tumor count and tumor size of visible tumors of lungs compared with B(a)p treatment alone, and NLRP3 deletion inhibited lung tumorigenesis induced by B(a)p or B(a)p plus LPS. Histopathological examination found LPS-induced pulmonary inflammatory changes enhanced lung tumorigenesis induced by B(a)p in WT mice, deletion of NLRP3 improved the inflammatory changes induced by LPS and the number and size of pathological tumor nests induced by B(a)p or B(a)p plus LPS. In addition, we found B(a)p treatment and B(a)p plus LPS treatment predominately induced the development of adenoma.

Conclusion

LPS enhanced B(a)p-induced lung tumorigenesis in WT and NLRP3−/− mice of C57BL/6J strain, and NLRP3 deletion inhibits lung tumorigenesis induced by B(a)p or B(a)p plus LPS.

Recombinant pyrin domain protein attenuates allergic inflammation by suppressing NF-κB pathway in asthmatic mice

Pyrin domain (PYD), a subclass of protein motif known as the death fold, is frequently involved in inflammation and immune responses. PYD modulates nuclear factor-kappa B (NF-κB) signalling pathway upon various stimuli. Herein, a novel recombinant pyrin domain protein (RPYD) was generated. Its role and mechanism in inflammatory response in an ovalbumin (OVA) induced asthma model was investigated. After OVA challenge, there was inflammatory cell infiltration in the lung, as well as airway hyper-responsiveness (AHR) to inhaled methacholine. In addition, eosinophils increased in the bronchoalveolar lavage fluids, alone with the elevated levels of Th-2 type cytokines [interleukin (IL)-4, IL-5 and IL-13], eotaxin, and adhesion molecules. However, the transnasal administration of RPYD before the OVA challenge significantly inhibited these asthmatic reactions. Moreover, RPYD markedly suppressed NF-κB translocation, reduced phosphorylation of p38 MAPK, and thus attenuated the expression of intercellular adhesion molecule 1 and IL-6 in the BEAS-2B cells stimulated by proinflammatory cytokines in vitro. These findings indicate that RPYD can protect asthma host from OVA-induced airway inflammation and AHR via down-regulation of NF-κB and p38 MAPK activities. RPYD may be used as a potential medicine for the treatment of asthma in clinic.

Analysis of gut microbiota revealed Lactococcus garviaeae could be an indicative of skin ulceration syndrome in farmed sea cucumber Apostichopus japonicus

Accumulative evidence has supported the pivotal roles of gut microbiota in shaping host health in a wide range of animals. However, the relationship between gut microbiota and sea cucumber disease is poorly understood. Using the Illumina sequencing of bacterial 16 S rRNA gene, we investigated the divergence of gut bacterial communities between healthy and skin ulceration syndrome (SUS) diseased Apostichopus japonicus. The results showed that bacterial phylotypes in both groups were closely related at phylum level with predominant component of Proteobacteria (>90%). However, Firmicutes and Verrucomicrobia displayed opposite trends in two groups with higher abundance of Firmicutes and lower of Verrucomicrobia in diseased group. Further KEGG enrichment revealed that bacterial-mediated infectious diseases and signal transduction pathways were significantly induced in the SUS group. We also identified one OTU of Lactococcus garvieae from Firmicutes exhibited significantly different abundances in diseased sea cucumber as compared to healthy subjects. The relative abundance of the species was 27.67% ± 10.52% in diseased group compared to 2.78% ± 2.59% in healthy sea cucumber. Three virulence genes of hlyⅢ, fbp and pva encoded by L. garvieae were investigated by qPCR, and were found to be significantly induced (P < 0.05) in diseased sea cucumbers as compared to healthy ones. All our results supported that L. garvieae might be a potential pathogen for SUS outbreak and could be served as a bio-indicator for this disease monitoring.

Nebulized lidocaine ameliorates allergic airway inflammation via downregulation of TLR2

Nebulized lidocaine has been suggested to be beneficial in asthma therapy, but the underlying mechanisms are little known. We aimed to investigate whether Toll-like receptor (TLR) 2 was involved in the protective effect of lidocaine on allergic airway inflammation. Female C57BL/6 mice were sensitized and challenged with ovalbumin (OVA). Meanwhile, some of the mice were treated with TLR2 agonist (Pam3CSK4, 100 μg) intraperitoneally in combination with OVA on day 0. Just after allergen provocation, mice were treated with inhaled lidocaine or vehicle for 30 min. In this model, we found that lidocaine markedly attenuated OVA-evoked airway inflammation, leukocyte recruitment and mucus production. Moreover, lidocaine abrogated the increased concentrations of T cytokines and TNF-α in bronchoalveolar lavage fluid (BALF) of allergic mice, as well as reducing the expression of phosphorylated nuclear factor (P-NF)-κBp65 and the NOD-like receptor pyridine containing 3 (NLRP3), which are important for the production of pro-inflammatory cytokines. In addition, our study showed that lidocaine dramatically decreased OVA-induced increased expression of TLR2 in the lung tissues. Furthermore, activation of TLR2 aggravated OVA-challenged airway inflammation, meanwhile, it also elevated OVA-induced expression of P-NF-κBp65 and NLRP3 in the lungs. However, lidocaine effectively inhibited airway inflammation and counteracted the expression of P-NF-κBp65 and NLRP3 in allergic mice pretreated with Pam3CSK4. Taken together, the present study demonstrated that lidocaine prevented allergic airway inflammation via TLR2 in an OVA-induced murine allergic airway inflammation model. TLR2/NF-κB/NLRP3 pathway may serve as a promising therapeutic strategy for allergic airway inflammation.

ATP/P2X7-NLRP3 axis of dendritic cells participates in the regulation of airway inflammation and hyper-responsiveness in asthma by mediating HMGB1 expression and secretion

The ATP/P2X7 axis of dendritic cells (DCs) mediates the activation of NLRP3 inflammasome and promotes secretion of interleukin (IL)-1β and IL-18 to induce T helper (Th) 2, Th17 differentiation in the pathogenesis of asthma. NLRP3 inflammasome also regulates high mobility protein 1 (HMGB1) release in DCs. Recent studies demonstrated the correlation between HMGB1 expression and airway inflammation and hyper-responsiveness (AHR) in asthma. However, the relationship between the ATP/P2X7-NLRP3 axis and HMGB1 in DCs in asthma is still unclear. ATP, apyrase, Brilliant Blue G, BzATP, glibenclamide, and Z-YVAD-FMK were administered to ovalbumin (OVA)-induced murine asthmatic model. For in vitro studies, bone marrow-derived mononuclear cells (BMDCs) were primed with LPS and stimulated with the same reagents. Activation of the ATP/P2X7 axis aggravated airway inflammation and AHR in the lung and induced Th2, Th17 polarization in asthmatic mice. Inhibition of NLRP3 inflammasome weakened cardinal features of asthma and blocked Th2, Th17 polarization. In vitro and vivo, ATP/P2X7 axis activated NLRP3 inflammasome and induced HMGB1 expression and release from DCs. Inhibition of NLRP3 inflammasome reduced HMGB1 expression and release. The ATP/P2X7-NLRP3 axis of DCs participates in mediating airway inflammation, AHR, and promoting Th2, Th17 inflammatory responses in asthmatic mice by inducing HMGB1 expression and secretion.

Andrographolide ameliorates OVA-induced lung injury in mice by suppressing ROS-mediated NF-κB signaling and NLRP3 inflammasome activation

In this study, we attempted to explore the effect and possible mechanism of Andrographolide on OVA-induced asthma. OVA challenge induced significant airway inflammatory cell recruitment and lung histological alterations, which were ameliorated by Andrographolide. The protein levels of cytokines in bron-choalveolar fluid (BALF) and serum were reduced by Andrographolide administration as well as the mRNA levels in lung tissue. Mechanically, Andrographolide markedly hampered the activation of nuclear factor-κB (NF-κB) and NLRP3 inflammasome both in vivo and vitro thus decreased levels of TNF-α and IL-1β. Finally, we confirmed that ROS scavenging was responsible for Andrographolide's inactivation of NF-κB and NLRP3 inflammasome signaling. Our study here revealed the effect and possible mechanism of Andrographolide on asthma, which may represent a new therapeutic approach for treating this disease.

Yupingfeng San Inhibits NLRP3 Inflammasome to Attenuate the Inflammatory Response in Asthma Mice

Yupingfeng San (YPFS) is a representative Traditional Chinese Medicine (TCM) formula with accepted therapeutic effect on Asthma. However, its action mechanism is still obscure. In this study, we used network pharmacology to explore potential mechanism of YPFS on asthma. Nucleotide-binding oligomerization domain (NOD)-like receptor pathway was shown to be the top one shared signaling pathway associated with both YPFS and asthma. In addition, NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome was treated as target protein in the process of YPFS regulating asthma. Further, experimental validation was done by using LPS-stimulated U937 cells and ovalbumin (OVA)-sensitized BALB/c mice model. In vitro experiments showed that YPFS significantly decreased the production of TNF-α and IL-6, as well as both mRNA and protein levels of IL-1β, NLRP3, Caspase-1 and ASC in LPS-stimulated U937 cells. In vivo experiment indicated that YPFS treatment not only attenuated the clinical symptoms, but also reduced inflammatory cell infiltration, mucus secretion and MUC5AC production in lung tissue of asthmatic mice. Moreover, YPFS treatment remarkably decreased the mRNA and protein levels of IL-1β, NLRP3, Caspase-1 and ASC in lung tissue of asthmatic mice. In conclusion, these results demonstrated that YPFS could inhibit NLRP3 inflammasome components to attenuate the inflammatory response in asthma.

Spleen tyrosine kinase inhibition ameliorates airway inflammation through modulation of NLRP3 inflammosome and Th17/Treg axis

Repeated exposure to the fungal pathogen Aspergillus fumigates triggers spleen tyrosine kinase (SYK) signalling through dectin-1 activation, which is associated with deleterious airway inflammation. β-Glucan-induced dectin-1 signalling activates the NLRP3 inflammasome, which in turn rapidly produces IL-1β, a master regulator of inflammation. IL-1β expression results in Th17/Treg imbalance, pulmonary inflammation, and bystander tissue injury. This study reports that 3,4 methylenedioxy-β-nitrostyrene (MNS), a potent SYK inhibitor, markedly decreased the expression of pro-inflammatory cytokines and increased the expression of anti-inflammatory cytokines in vitro. Furthermore, SYK inhibition markedly decreased β-glucan-induced IL-1β expression, suggesting that SYK is indispensable for NLRP3 inflammasome activation. Decreased IL-1β expression correlated with reduced Th17 response and enhanced immunosuppressive Treg response. Notably, SYK inhibition ameliorated inflammation caused by repeated intranasal β-glucan challenge in BALB/C mice. SYK inhibition also restored the Th17/Treg balance via decreased Th17 and increased Treg responses, as evidenced by decreased IL-17 and ror-γ levels. Additionally, inhibition of SYK increased IL-10 secreting CD4⁺FOXP3⁺ T cells that accompanied reduced T cell proliferation. Decreased IgA in the Bronchoalveolar lavage (BAL) fluid and serum also indicated the immunosuppressive potential of SYK inhibition. Histopathology data revealed that repeated β-glucan challenge caused substantial pulmonary damage, as indicated by septal thickening and interstitial lymphocytic, neutrophil and granulocyte recruitment. These processes were effectively prevented by SYK inhibition, resulting in lung protection. Collectively, our findings suggest that SYK inhibition ameliorates dectin-1- mediated detrimental pulmonary inflammation and subsequent tissue damage. Therefore, SYK can be a new target gene in the therapeutic approach against fungal induced airway inflammation.

Mycoplasma pneumoniae from the Respiratory Tract and Beyond

Mycoplasma pneumoniae is an important cause of respiratory tract infections in children as well as adults that can range in severity from mild to life-threatening. Over the past several years there has been much new information published concerning infections caused by this organism. New molecular-based tests for M. pneumoniae detection are now commercially available in the United States, and advances in molecular typing systems have enhanced understanding of the epidemiology of infections. More strains have had their entire genome sequences published, providing additional insights into pathogenic mechanisms. Clinically significant acquired macrolide resistance has emerged worldwide and is now complicating treatment. In vitro susceptibility testing methods have been standardized, and several new drugs that may be effective against this organism are undergoing development. This review focuses on the many new developments that have occurred over the past several years that enhance our understanding of this microbe, which is among the smallest bacterial pathogens but one of great clinical importance.

Hydrogen Sulfide Prevents and Partially Reverses Ozone-Induced Features of Lung Inflammation and Emphysema in Mice

Hydrogen sulfide (H2S), a novel signaling gasotransmitter in the respiratory system, may have antiinflammatory properties in the lung. We examined the preventive and therapeutic effects of H2S on ozone-induced features of lung inflammation and emphysema. C57/BL6 mice were exposed to ozone or filtered air over 6 weeks. Sodium hydrogen sulfide (NaHS), an H2S donor, was administered to the mice either before ozone exposure (preventive effect) or after completion of 6 weeks of ozone exposure (therapeutic effect). The ozone-exposed mice developed emphysema, measured by micro-computed tomography and histology, airflow limitation, measured by the forced maneuver system, and increased lung inflammation with augmented IL-1β, IL-18, and matrix metalloproteinase-9 (MMP-9) gene expression. Ozone-induced changes were associated with increased Nod-like receptor pyrin domain containing 3 (NLRP3)-caspase-1 activation and p38 mitogen-activated protein kinase phosphorylation and decreased Akt phosphorylation. NaHS both prevented and reversed lung inflammation and emphysematous changes in alveolar space. In contrast, NaHS prevented, but did not reverse, ozone-induced airflow limitation and bronchial structural remodeling. In conclusion, NaHS administration prevented and partially reversed ozone-induced features of lung inflammation and emphysema via regulation of the NLRP3-caspase-1, p38 mitogen-activated protein kinase, and Akt pathways.

Inhibition of NLRP3 Inflammasome Prevents LPS-Induced Inflammatory Hyperalgesia in Mice: Contribution of NF-κB, Caspase-1/11, ASC, NOX, and NOS Isoforms

The nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3), an intracellular signaling molecule that senses many environmental- and pathogen/host-derived factors, has been implicated in the pathogenesis of several diseases associated with inflammation. It has been suggested that NLRP3 inflammasome inhibitors may have a therapeutic potential in the treatment of NLRP3-related inflammatory diseases. The aim of this study was to determine whether inhibition of NLRP3 inflammasome prevents inflammatory hyperalgesia induced by lipopolysaccharide (LPS) in mice as well as changes in expression/activity of nuclear factor κB (NF-κB), caspase-1/11, nicotinamide adenine dinucleotide phosphate oxidase (NOX), and endothelial/neuronal/inducible nitric oxide synthase (eNOS/nNOS/iNOS) that may regulate NLRP3/apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)/pro-caspase-1 inflammasome formation and activity by using a selective NLRP3 inflammasome inhibitor, MCC950. Male mice received saline (10 ml/kg; i.p.), LPS (10 mg/kg; i.p.), and/or MCC950 (3 mg/kg; i.p.). Reaction time to thermal stimuli within 1 min was evaluated after 6 h. The mice were killed and the brains, hearts, and lungs were collected for measurement of NF-κB, caspase-1, caspase-11, NLRP3, ASC, NOX subunits (gp91^phox; NOX2), and p47^phox; NOXO2), nitrotyrosine, eNOS, nNOS, iNOS, and β-actin protein expression, NOS activity, and interleukin (IL)-1β levels. LPS-induced hyperalgesia was associated with a decrease in eNOS, nNOS, and iNOS protein expression and activity as well as an increase in expression of NF-κB p65, caspase-1 p20, caspase-11 p20, NLRP3, ASC, gp91^phox, p47^phox, and nitrotyrosine proteins in addition to elevated IL-1β levels. The LPS-induced changes were prevented by MCC950. The results suggest that inhibition of NLRP3/ASC/pro-caspase-1 inflammasome formation and activity prevents inflammatory hyperalgesia induced by LPS in mice as well as changes in NF-κB, caspase-11, NOX2, NOXO2, and eNOS/nNOS/iNOS expression/activity.

Role of NLRP3 Inflammasome in Eosinophilic and Non-eosinophilic Chronic Rhinosinusitis with Nasal Polyps

The pathophysiologic mechanisms of human chronic rhinosinusitis with nasal polyps (CRSwNP) remain unclear. We aimed to elucidate expression and biologic role of NLRP3 inflammasome in CRSwNP. Immunohistochemistry (IHC) was conducted to assess NLRP3 immunolabeling, real-time polymerase chain reaction (PCR) was used for IL-9 and NLRP3, and caspase-1 level quantitation in CRSwNP and control subjects. In addition, enzyme-linked immunosorbent assay (ELISA) was employed for analyzing concentrations of IL-1β and IL-18 in the homogenates prepared from tissue specimens. Moreover, human nasal epithelial cells (HNECs) were used to evaluate the effects of lipopolysaccharide (LPS) and glyburide on NLRP3 inflammasome signaling pathway. Results showed that NLRP3 and caspase-1 were overexpressed in CRSwNP, especially in eosinophilic CRSwNP (ECRSwNP). Interestingly, NLRP3 expression had close correlation to that of caspase-1. Concentrations of IL-1β and IL-18 were elevated. NLRP3 inflammasome signaling pathway was augmented by LPS but suppressed by glyburide. In conclusion, NLRP3 inflammasome signaling pathway played a pro-inflammatory role in the pathogenesis of CRSwNP, especially in ECRSwNP. NLRP3 inflammasome signaling pathway was augmented by LPS, but suppressed by glyburide.

Inflammasome Activation by ATP Enhances Citrobacter rodentium Clearance through ROS Generation

BACKGROUND

Nod-like receptor family, pyrin domain containing 3 (NLRP3) is an important cytosolic sensor of cellular stress and infection. Once activated, NLRP3 forms a multiprotein complex (inflammasome) that triggers the maturation and secretion of interleukin (IL)-1β and IL-18. We aimed to define the consequences of NLRP3 induction, utilizing exogenous adenosine triphosphate (ATP) as an inflammasome activator, to determine if inflammasome activation increases macrophage killing of Citrobacter rodentium and define mechanisms.

METHODS

Bacterial survival was measured using a gentamicin protection assay. Inflammasome activation or inhibition in mouse J774A.1 macrophages were assessed by measuring IL-1β; cytokines and reactive oxygen species (ROS) were measured by ELISA and DCFDA, respectively.

RESULTS

Activation of the inflammasome increased bacterial killing by macrophages and its inhibition attenuated this effect with no impact on phagocytosis or cell death. Furthermore, inflammasome activation suppressed pro-inflammatory cytokines during infection, possibly due to more effective bacterial killing. While the infection increased ROS production, this effect was reduced by inflammasome inhibitors, indicating that ROS is inflammasome-dependent. ROS inhibitors increased bacterial survival in the presence of ATP, suggesting that inflammasome-induced bacterial killing is mediated, at least in part, by ROS activity.

CONCLUSION

Improving inflammasome activity during infection may increase bacterial clearance by macrophages and reduce subsequent microbe-induced inflammation.