Ameliorative effect of selective NLRP3 inflammasome inhibitor MCC950 in an ovalbumin-induced allergic rhinitis murine model

The role of NLRP3 inflammasome in type 2 inflammation related diseases

Type 2 inflammation related diseases, such as atopic dermatitis, asthma, and allergic rhinitis, are diverse and affect multiple systems in the human body. It is common for individuals to have multiple co-existing type 2 inflammation related diseases, which can impose a significant financial and living burden on patients. However, the exact pathogenesis of these diseases is still unclear. The NLRP3 inflammasome is a protein complex composed of the NLRP3 protein, ASC, and Caspase-1, and is activated through various mechanisms, including the NF-κB pathway, ion channels, and lysosomal damage. The NLRP3 inflammasome plays a role in the immune response to pathogens and cellular damage. Recent studies have indicated a strong correlation between the abnormal activation of NLRP3 inflammasome and the onset of type 2 inflammation. Additionally, it has been demonstrated that suppressing NLRP3 expression effectively diminishes the inflammatory response, highlighting its promising therapeutic applications. Therefore, this article reviews the role of NLRP3 inflammasome in the development and therapy of multiple type 2 inflammation related diseases.

NLRP3 promotes allergic responses to birch pollen extract in a model of intranasal sensitization

Introduction & Objective

Allergic sensitization is an essential step in the development of allergic airway inflammation to birch pollen (BP); however, this process remains to be fully elucidated. Recent scientific advances have highlighted the importance of the allergen context. In this regard, microbial patterns (PAMPs) present on BP have attracted increasing interest. As these PAMPs are recognized by specialized pattern recognition receptors (PRRs), this study aims at investigating the roles of intracellular PRRs and the inflammasome regulator NLRP3.

Methods

We established a physiologically relevant intranasal and adjuvant-free sensitization procedure to study BP-induced systemic and local lung inflammation.

Results

Strikingly, BP-sensitized Nlrp3-deficient mice showed significantly lower IgE levels, Th2-associated cytokines, cell infiltration into the lung, mucin production and epithelial thickening than their wild-type counterparts, which appears to be independent of inflammasome formation. Intriguingly, bone-marrow chimera revealed that expression of NLRP3 in the hematopoietic system is required to trigger an allergic response.

Conclusion

Overall, this study identifies NLRP3 as an important driver of BP-induced allergic immune responses.

Xiaoqinglong decoction improves allergic rhinitis by inhibiting NLRP3-mediated pyroptosis in BALB/C mice

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoqinglong decoction (XQLD), first recorded in Shang Han Lun, is a traditional Chinese medicine prescribed for the treatment of allergic rhinitis (AR). XQLD alleviates the clinical symptoms of AR by inhibiting the occurrence of an inflammatory response, but the specific regulatory mechanism remains unclear.

AIM OF THE STUDY

NLRP3-mediated pyroptosis is closely related to AR pathogenesis. Hence, this study aimed to explore the potential role of NLRP3-mediated pyroptosis pathway in the AR-associated pharmacological mechanism of XQLD.

MATERIALS AND METHODS

BALB/C mice models of AR was established by using ovalbumin (OVA) and aluminum hydroxide sensitization. After intragastric administration of different dosages of XQLD, nasal allergic symptoms were observed. The expression of OVA-sIgE and Th2 inflammatory factors (IL-4, IL-5, and IL-13) in serum was detected by ELISA. The histopathological morphology and expression of inflammatory factors in nasal mucosa along with pyroptosis were investigated. Molecular docking was performed to analyze the binding of representative compounds of XQLD with NLRP3. Activation of the NLRP3 inflammasome was detected by immunofluorescence and western blotting.

RESULTS

XQLD significantly improved the nasal allergic symptoms of mice, reduced the degree of goblet cell proliferation, mast cell infiltration, and collagen fiber hyperplasia in nasal mucosa. Meanwhile, it could downregulate the expression of Th2 inflammatory factors (IL-4, IL-5, and IL-13) in serum and nasal mucosa. XQLD significantly reduced the number of GSDMD and TUNEL double-positive cells and IL-1β and IL-18 expression. Molecular docking confirmed that seven representative compounds of XQLD had good binding properties with NLRP3 and were able to inhibit the activation of the NLRP3 inflammasome.

CONCLUSIONS

The representative compounds of XQLD might inhibit pyroptosis in nasal mucosa mediated by the NLRP3 inflammasome to helping the recovery of AR, which provides a new modern pharmacological proof for XQLD to treat AR.

Monocyte NLRP3 inflammasome and interleukin-1β activation modulated by alpha-1 antitrypsin therapy in deficient individuals

INTRODUCTION

Altered complement component 3 (C3) activation in patients with alpha-1 antitrypsin (AAT) deficiency (AATD) has been reported. To understand the potential impact on course of inflammation, the aim of this study was to investigate whether C3d, a cleavage-product of C3, triggers interleukin (IL)-1β secretion via activation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome. The objective was to explore the effect of AAT augmentation therapy in patients with AATD on the C3d/complement receptor 3 (CR3) signalling axis of monocytes and on circulating pro-inflammatory markers.

METHODS

Inflammatory mediators were detected in blood from patients with AATD (n=28) and patients with AATD receiving augmentation therapy (n=19). Inflammasome activation and IL-1β secretion were measured in monocytes of patients with AATD, and following C3d stimulation in the presence or absence of CR3 or NLRP3 inhibitors.

RESULTS

C3d acting via CR3 induces NLRP3 and pro-IL-1β production, and through induction of endoplasmic reticulum (ER) stress and calcium flux, triggers caspase-1 activation and IL-1β secretion. Treatment of individuals with AATD with AAT therapy results in decreased plasma levels of C3d (3.0±1.2 µg/mL vs 1.3±0.5 µg/mL respectively, p<0.0001) and IL-1β (115.4±30 pg/mL vs 73.3±20 pg/mL, respectively, p<0.0001), with a 2.0-fold decrease in monocyte NLRP3 protein expression (p=0.0303), despite continued ER stress activation.

DISCUSSION

These results provide strong insight into the mechanism of complement-driven inflammation associated with AATD. Although the described variance in C3d and NLRP3 activation decreased post AAT augmentation therapy, results demonstrate persistent C3d and monocyte ER stress, with implications for new therapeutics and clinical practice.

The study of the role of purified anti-mouse CD193 (CCR3) antibody in allergic rhinitis mouse animal models

The pathogenesis of allergic asthma is similar to that of allergic rhinitis, with inflammation cells producing and releasing inflammatory mediators and cytokines closely related to CCR3.Based on the theory of "one airway, one disease", the use of CCR3 monoclonal antibody may have a similar effect on allergic rhinitis. However, there are few studies on CCR3 monoclonal antibody in allergic rhinitis. Therefore, the aim of this study was to investigate the effective concentration of CCR3 monoclonal antibody, to compare the effects of different methods of administration, and to examine the lung condition of allergic mice to investigate whether antibody treatment protects the lungs. In this study, we constructed a mouse model of allergic rhinitis and intraperitoneally injected different doses of CCR3 monoclonal antibody (5, 10, and 20 uL/mg) to observe its therapeutic effect: observing changes in tissue morphology of nasal mucosa, infiltration of inflammation, and using ELISA to detect changes in relevant inflammatory mediators and cytokines, studying the role of CCR3 mAb in inhibiting CCR3-related actions on the nasal mucosa of allergic rhinitis mice. Furthermore, In addition, the therapeutic effects of intraperitoneal injection (i.p.) and intranasal administration (i.n.) were studied on the basis of effective concentrations.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Understanding the role of NLRP3-mediated pyroptosis in allergic rhinitis: A review

Allergic rhinitis (AR) is a chronic, inflammatory disease of the nasal mucosa, caused by the immunoglobulin E-mediated immune response. The annual incidence rate of AR is on the rise, exerting a significant impact on individuals' physical and mental wellbeing. The treatment effect in some patients is still not ideal, as the pathogenesis of AR is complex and diverse. Recent studies have shown that NLRP3 inflammasome-mediated pyroptosis is widely involved in the occurrence and development of AR through various pathways. This article reviews the mechanism of pyroptosis and its research progress in the field of AR, and puts forward possible therapeutic targets to offer innovative approaches for its management.

ACT001 Ameliorates ionizing radiation-induced lung injury by inhibiting NLRP3 inflammasome pathway

Radiotherapy is a prevalent treatment modality for thoracic tumors; however, it can lead to radiation-induced lung injury (RILI), which currently lacks effective interventions. ACT001, a prodrug of micheliolide, has demonstrated promising clinical application potential, yet its impact on RILI requires further validation. This study aims to investigate the radioprotective effects of ACT001 on RILI and elucidate its underlying mechanism. Sprague-Dawley rats were utilized to induce RILI following 20 Gy X-ray chest irradiation, and lung tissue inflammation and fibrosis were assessed using hematoxylin and eosin (H&E) and Masson staining. Lung injury, inflammation, and oxidative stress markers were evaluated employing commercial kits. Pyroptosis-related differentially expressed genes (DEGs) were analyzed using a microarray dataset from the Gene Expression Omnibus (GEO) database, and their functions and hub genes were identified through protein-protein interaction networks. Pyroptosis-related genes were detected via RT-qPCR, western blotting, immunofluorescence, and immunohistochemistry. The results demonstrated that ACT001 ameliorated RILI, diminished pro-inflammatory cytokine release and fibrosis, and mitigated the activation of the NLRP3 inflammasome while inhibiting pyroptosis in lung tissue. In conclusion, our study reveals that ACT001 can suppress NLRP3 inflammasome-mediated pyroptosis and improve RILI, suggesting its potential as a novel protective agent for RILI.

Mechanism of Kruppel-Like Factor 4 in Pyroptosis of Nasal Mucosal Epithelial Cells in Mice With Allergic Rhinitis

BACKGROUND

Allergic rhinitis (AR) is a chronic nasal inflammation, characterized by nasal epithelial dysfunction. Gene therapy targeting transcription factors is a promising strategy for quenching allergic inflammation, including AR.

OBJECTIVE

This study sought to probe the mechanism of Kruppel-like factor 4 (KLF4) in pyroptosis of nasal mucosal epithelial cells (NEpCs) in AR mice and provide targets for AR treatment.

METHODS

AR mouse models were established using sensitization with ovalbumin, followed by injection with short hairpin RNA KLF4 (sh-KLF4). AR symptoms were assessed by the times of sneezing and nose rubbing, hematoxylin-eosin, and periodic acid-Schiff staining. Levels of KLF4, nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3), cleaved caspase-1, and N-terminal domain (GSDMD-N) in nasal mucosal tissues were determined by Western blot assay, and levels of interleukin (IL)-1β and IL-18 in nasal lavage fluid were determined by enzyme-linked immunosorbent assay. The binding of KLF4 to the NLRP3 promoter was verified using chromatin immunoprecipitation and dual-luciferase assays. The functional rescue experiment was performed with oe-NLRP3 and sh-KLF4 in AR mice.

RESULTS

KLF4 was upregulated in nasal mucosal tissues of AR mice. KLF4 inhibition reduced the times of sneezing and nose rubbing, inflammatory cell infiltration, and goblet cell hyperplasia in nasal mucosal tissues, and levels of NLRP3, cleaved caspase-1, GSDMD-N, IL-1β, and IL-18. KLF4 was enriched on the NLRP3 promoter and improved NLRP3 expression. NLRP3 overexpression reversed the inhibition of sh-KLF4 on pyroptosis of NEpCs in AR mice.

CONCLUSION

KLF4 bound to the NLRP3 promoter and promoted pyroptosis of NEpCs in AR mice via activating NLRP3.

The NLRP3 inflammasome as a new target in respiratory disorders treatment

In recent years a continuous increase in new cases of respiratory disorders, such as rhinitis, asthma, and chronic obstructive pulmonary disease (COPD), has been observed. The exact pathomechanism of these diseases is still blurry, resulting in the lack of targeted and effective therapy. The conventional use of treatment strategies, such as antihistamine drugs and/or glucocorticosteroids act mainly symptomatically and have significant side effects. Specific allergen immunotherapy is only useful in the management of specific allergies and selected patients. Therefore, new therapeutic solutions are constantly being sought. The novelty of recent years has been the association between NLRP3 inflammasome activation and the development of airway inflammatory diseases. This seems to be an interesting therapeutic target that may support or even replace traditional therapies in the future. The review presented, discusses the contribution of NLRP3 inflammasome to the development of allergic rhinitis, allergic asthma, and COPD. Moreover, the modulatory properties of probiotics as potential inhibitors of NLRP3 inflammasome are emphasised.

Influences of miR-378a-3p on the Pathogenesis of Allergic Rhinitis via GzmB-Mediated Inflammatory Reaction

Methods

Totally, 24 BALB/c mice were assigned to the AR group, control group, GzmB group, and blank group (each n = 6). The blank group was normally fed without treatment, and the other three groups were treated by ovalbumin (OVA) to induce AR models, in which the GzmB group was intranasally injected with lentiviral vector suppressing GzmB expression during the second immunization, while the control group was given the GzmB-blank vector. The times of AR pathological behaviours such as sneezing and scratching the nose of mice were observed and counted. The nasal lavage fluid of each mouse was acquired, and then, the mouse was executed by cervical dislocation, followed by collection of blood and nasal mucosa tissues. Then, ELISA was adopted for quantifying immunoglobulin E (IgE), interleukin (IL)-4, IL-6, and histamine (HA), and nasal mucosa tissues were treated by HE and TUNEL staining to observing their histopathological manifestations. PCR and western blot (WB) were adopted for quantifying GzmB and miR-378a-3p. Additionally, with NP69 cells, dual luciferase reporter (DLR) assay was carried out for determining the targeting association of GzmB with miR-378a-3p. Another 24 mice were assigned to the AR group, GzmB group, miR-378a-3p group, and GzmB+ miR-378a-3p group (each n = 6). The AR and GzmB groups were treated as above. The miR-378a-3p group was intervened by lentiviral vector suppressing miR-378a-3p, while the GzmB+ miR-378a-3p group was given GzmB and lentiviral vector suppressing miR-378a-3p meantime. A rescue assay was conducted through repeating the above tests.

Results

The times of sneezing and rubbing the nose and the levels of IgE, IL-4, IL-6, and HA were similar between the control and AR groups (all P > 0.05), and these items of the two groups were all higher than those of the blank and GzmB groups (all P < 0.05). However, no notable difference was observed in IL-4 and IL-6 levels between the GzmB and blank groups (both P > 0.05), while higher levels of other detection results were found in the former group than in the latter (all P < 0.05). The staining results revealed obvious congestion, oedema, and necrosis structures in the nasal mucosa epithelium of the control and AR groups and also revealed a large number of infiltrating eosinophils and notable increase of apoptotic nasal mucosa epithelial cells. The GzmB group showed notably improved nasal mucosa tissues, and its infiltration and apoptosis of eosinophils were more notable than those of the blank group, but notably weaker than those of the AR and control groups. Additionally, the PCR and WB results revealed similar miR-378a-3p and GzmB levels in nasal mucosa between the control and AR groups (both P > 0.05), and a notable decrease of miR-378a-3p and a notable increase of GzmB in both groups (both P < 0.05). The DLR assay revealed notably suppressed fluorescence activity of GzmB-WT in NP69 cells after transfection of miR-378a-3p mimics (P < 0.05) and notably down regulated GzmB protein after increase of miR-378a-3p (P<0.05). Finally, the rescue assay revealed that downregulating miR-378a-3p aggravated the pathological changes of AR (P < 0.05) and also completely reversed the impacts of inhibiting GzmB on the pathological behaviours of AR mice.

Conclusions

MiR-378a-3p can accelerate the pathological development of AR through targeted inhibition on the release of pro-inflammatory factors such as IgE and HA activated by GzmB, so it is a promising molecular target of AR therapy and offers a novel research direction for the complete cure of AR.

Pneumococcal Δpep27 Immunization Attenuates TLRs and NLRP3 Expression and Relieves Murine Ovalbumin-Induced Allergic Rhinitis

Allergic rhinitis (AR), one of the most common inflammatory diseases, is caused by immunoglobulin E (IgE)-mediated reactions against inhaled allergens. AR involves mucosal inflammation driven by type 2 helper T (Th2) cells. Previously, it was shown that the Streptococcus pneumoniae pep27 mutant (Δpep27) could prevent and treat allergic asthma by reducing Th2 responses. However, the underlying mechanism of Δpep27 immunization in AR remains undetermined. Here, we investigated the role of Δpep27 immunization in the development and progression of AR and elucidated potential mechanisms. In an ovalbumin (OVA)-induced AR mice model, Δpep27 alleviated allergic symptoms (frequency of sneezing and rubbing) and reduced TLR2 and TLR4 expression, Th2 cytokines, and eosinophil infiltration in the nasal mucosa. Mechanistically, Δpep27 reduced the activation of the NLRP3 inflammasome in the nasal mucosa by down-regulating the Toll-like receptor signaling pathway. In conclusion, Δpep27 seems to alleviate TLR signaling and NLRP3 inflammasome activation to subsequently prevent AR.

Neuroprotective effects of CysLTR antagonist on Streptococcus pneumoniae‑induced meningitis in rats

Cysteinyl leukotrienes (CysLTs) modulate central nervous system inflammatory responses via their receptors, CysLT₁R and CysLT₂R. It has been demonstrated that CysLTR participates in the infection process of Streptococcus pneumoniae (SP)-induced meningitis. In the present study, the effects and possible underlying mechanisms of CysLTR antagonists (pranlukast and HAMI 3379) on SP meningitis were further determined. SP meningitis was induced by intracerebroventricular injection of serotype III SP in Sprague-Dawley rats which were administrated intraperitoneally with 0.1 mg/kg antagonists. The clinical disease status of rats was evaluated by body weight and behavioral changes with neurological scoring. Survival neuron density, activated microglial and astrocytes were assessed by Nissl staining and immunohistochemical staining. The expression levels of inflammatory cytokines and NLRP3 inflammasome were detected by reverse transcription-quantitative PCR and western blotting, respectively. Pranlukast and HAMI 3379 treatment markedly alleviated the clinical disease status, which was manifested by improving body weight loss and neurological deficit. Furthermore, pranlukast and HAMI 3379 treatment ameliorated neuronal injury and inhibited microgliosis and astrogliosis. In addition, significant downregulation of inflammatory cytokines and NLRP3 expression was observed in pranlukast and HAMI 3379-treated rats. These in vivo findings indicated the neuroprotective effects of CysLTR antagonists against experimental SP-induced meningitis, and the mechanism of anti-inflammatory effects may partly be by inhibiting NLRP3 inflammasome overactivation.

Fine particulate matter exposure exacerbated nasal mucosal damage in allergic rhinitis mice via NLRP3 mediated pyroptosis

BACKGROUND

The incidence of nasal allergy/allergic rhinitis (AR) is rising worldwide, which has become a serious public health problem. Epidemiological studies point that exposure to environmental PM2.5 is closely linked to AR aggravation, however, the exactly mechanism is not clear. This study was performed to reveal molecular mechanisms of PM2.5 -induced AR deterioration.

METHODS

Morphology and element analysis of PM2.5 was examined by scanning electron microscopy (SEM) and Energy Dispersive Spectrometer (EDS). A total of 24 female C57BL/6 mice were divided into three groups (control group, AR group, and PM2.5 + AR group, each group contains 8 mice). Mice from AR group and PM2.5 + AR group were intraperitoneally injected with OVA suspension (0.004% OVA+3% aluminum hydroxide) on days 1, 7, and 14. 0.2 mL /kg B.W. for sensitization; then the same mice were intranasal instilled with 5% OVA solution daily for 7 days to established AR mice model (each nostril for 10 μl, day 15-21). The mice were intranasal instilled PBS (control group and AR group, each nostril for 10 μl) or PM2.5 (AR + PM2.5 group, 4.0 mg/kg b.w., each nostril for 10 μl) at the same way from day 23-29. The nasal symptoms were evaluated after the last instillation of PM2.5. Pathological changes and ultrastructure of nasal mucosa were observed by HE staining and SEM. Goblet cells hyperplasia was performed by Periodic acid-Schiff (PAS) staining. NLRP3, Caspase-1, GSDMD and IL-1β protein expression were assessed by immunohistochemical (IHC) staining.

RESULTS

Exposure to PM2.5 aggravated rhinitis symptom, promoted the secretion of serum IgE level and destroyed ultrastructural of nasal mucosa. Interestingly, NLRP3, Caspase-1 GSDMD and IL-1β protein expression were obviously elevated. NLRP3 /Capase-1/ GSDMD meditated cell pyroptosis participated in the process of AR exacerbation. However, macrophage is not the main effector cell.

CONCLUSION

PM2.5 exposure induces aggravation of allergic rhinitis, which is related to NLRP3 inflammasome meditated caspase-1 activation and cell pyroptosis in nasal mucosal.

MCC950 attenuates doxorubicin-induced myocardial injury in vivo and in vitro by inhibiting NLRP3-mediated pyroptosis

MCC950, an NLRP3 inflammasome inhibitor, displays multiple pharmacological properties. However, the protective potential and underlying mechanism of MCC950 against doxorubicin (DOX)-induced myocardial injury has not been well investigated yet. Herein, DOX-induced myocardial injury in mice and in H9c2 myocardial cells was investigated, and the protective effects and underlying mechanism of MCC950 were fully explored. The results showed that MCC950 co-treatment significantly improved myocardial function, inhibited inflammatory and myocardial fibrosis, and attenuated cardiomyocyte pyroptosis in DOX-treated mice. Mechanismly, MCC950 had the potential to inhibit DOX-induced the cleavage of NLRP3, ASC, Caspase-1, IL-18, IL-1β and GSDMD in vivo. Moreover, MCC950 co-treatment in vivo suppressed DOX-induced cytotoxicity as well as inflammatory and cardiomyocyte pyroptosis through the same molecular mechanism. Taken together, our findings validated that MCC950, an NLRP3 inflammasome inhibitor, has the potential to attenuate doxorubicin-induced myocardial injury in vivo and in vitro by inhibiting NLRP3-mediated pyroptosis.

Knockdown of miR‑205‑5p alleviates the inflammatory response in allergic rhinitis by targeting B‑cell lymphoma 6

Allergic rhinitis (AR) is an IgE-mediated upper airway disease with a high worldwide prevalence. MicroRNA (miR)-205-5p upregulation has been observed in AR; however, its role is poorly understood. The aim of the present study was to investigate the effect of miR-205-5p on AR-associated inflammation. To establish an AR model, BALB/c mice were sensitized using an intraperitoneal injection of ovalbumin (OVA) on days 0, 7 and 14, followed by intranasal challenge with OVA on days 21–27. A lentiviral sponge for miR-205-5p was used to downregulate miR-205-5p in vivo via intranasal administration on days 20–26. Reverse transcription-quantitative PCR revealed that miR-205-5p was upregulated in AR mice. Notably, miR-205-5p knockdown reduced the frequency of nose-rubbing and sneezing, and attenuated pathological alterations in the nasal mucosa. The levels of total and OVA-specific IgE, cytokines IL-4, IL-5 and IL-13, and inflammatory cells, were decreased by miR-205-5p knockdown in AR mice. In addition, miR-205-5p knockdown inhibited nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation by reducing the expression levels of NLRP3, apoptosisassociated specklike protein containing a CARD, cleaved caspase-1 and IL-1β by western blot analysis. B-cell lymphoma 6 (BCL6) was confirmed as a target of miR-205-5p by luciferase reporter assay. In conclusion, the present findings suggested that miR-205-5p knockdown may attenuate the inflammatory response in AR by targeting BCL6, which may be a potential therapeutic target for AR.

Fine particulate matter-induced lung inflammation is mediated by pyroptosis in mice

BACKGROUND

Exposure to ambient air-borne fine particulate matter (PM_2.5) increases respiratory morbidity and mortality. The mechanisms underlying PM_2.5-induced adverse effects remain unclear. This study aimed to uncover the molecular mechanisms of PM_2.5-induced lung toxicity using a mouse model.

METHODS

Scanning electron microscopy and inductively coupled plasma mass spectrometry were used to examine and analyze PM_2.5 morphology and element compositions, respectively. Twenty four male mice were randomly divided into three groups: control (PBS), PM_2.5 (4.0 mg/kg b.w.), and PM_2.5 + Z-YVAD-FMK. In the latter group, the pan-caspase inhibitor (Z-YVAD-FMK) was intraperitoneally injected into mice at a dose of 12.5 mg/kg body weight prior to intratracheal instillation of PM_2.5 (4.0 mg/kg b.w.) every other day for a total of 3 times (n = 8 in each group). Bronchoalveolar lavage fluids (BALFs) were collected 24 h after the last instillation of PM_2.5. Levels of total proteins (TP), lactate dehydrogenase (LDH), IL-1β and IL-18 were analyzed for biomarkers of cell injury and inflammation. Additionally, histological alterations of lung tissues were assessed by hematoxylin-eosin staining. mRNA and protein expression of Caspase1, NLRP3 and GSDMD were examined by real-time fluorescent quantitative PCR and immunohistochemical staining.

RESULTS

Exposure to PM_2.5 increased levels of TP, LDH, IL-1β, IL-18 and inflammatory cell counts in lung. The mRNA and protein expression of Caspase1, NLRP3 and GSDMD were increased. Inhibition of the NALRP3/Caspase-1 signaling pathway ameliorated PM_2.5-induced lung injury and inflammation, partially through suppressing pyroptosis in lung.

CONCLUSION

PM_2.5 exposure induces lung injury and inflammation, which is mediated by the NALRP3/Caspase-1 signaling pathway.

Pharmacological Inhibition of the Nod-Like Receptor Family Pyrin Domain Containing 3 Inflammasome with MCC950

Activation of the Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome drives release of the proinflammatory cytokines interleukin (IL)-1β and IL-18 and induces pyroptosis (lytic cell death). These events drive chronic inflammation, and as such, NLRP3 has been implicated in a large number of human diseases. These range from autoimmune conditions, the simplest of which is NLRP3 gain-of-function mutations leading to an orphan disease, cryopyrin-associated period syndrome, to large disease burden indications, such as atherosclerosis, heart failure, stroke, neurodegeneration, asthma, ulcerative colitis, and arthritis. The potential clinical utility of NLRP3 inhibitors is substantiated by an expanding list of indications in which NLRP3 activation has been shown to play a detrimental role. Studies of pharmacological inhibition of NLRP3 in nonclinical models of disease using MCC950 in combination with human genetics, epigenetics, and analyses of the efficacy of biologic inhibitors of IL-1β, such as anakinra and canakinumab, can help to prioritize clinical trials of NLRP3-directed therapeutics. Although MCC950 shows excellent (nanomolar) potency and high target selectivity, its pharmacokinetic and toxicokinetic properties limited its therapeutic development in the clinic. Several improved, next-generation inhibitors are now in clinical trials. Hence the body of research in a plethora of conditions reviewed herein may inform analysis of the potential translational value of NLRP3 inhibition in diseases with significant unmet medical need. SIGNIFICANCE STATEMENT: The nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is one of the most widely studied and best validated biological targets in innate immunity. Activation of NLRP3 can be inhibited with MCC950, resulting in efficacy in more than 100 nonclinical models of inflammatory diseases. As several next-generation NLRP3 inhibitors are entering proof-of-concept clinical trials in 2020, a review of the pharmacology of MCC950 is timely and significant.

RGFP966, a selective HDAC3 inhibitor, ameliorates allergic and inflammatory responses in an OVA-induced allergic rhinitis mouse model

RGFP966 is a selective inhibitor of histone deacetylase 3 (HDAC3) playing crucial roles in triggering allergic and inflammatory responses. Whereas, its role in allergic rhinitis (AR) remains uncertain. This study sought to illustrate the role and mechanism of HDAC3 inhibitor RGFP966 on allergic and inflammatory responses in murine AR. RGFP966 administration was applied on murine AR. HE staining, PAS staining, toluidine blue staining, immunohistochemistry staining and real-time PCR methods were used to assess eosinophils, goblet cells, mast cells, HDAC3 positive cells and mRNA levels in nasal tissues of mice. HDAC3 activities in nasal tissues were quantified with HDAC3 Activity Assay Kit. We collected blood and nasal lavage fluid (NLF) of mice for assaying IgE, inflammatory cytokines and inflammatory cells. Results indicated that RGFP966 intervention attenuated sneezing, nose rubbing, IgE, inflammatory cytokines, eosinophils, goblet cells, mast cells, inflammatory cells, HDAC3 levles and activities in RGFP966 treated mice. In conclusion, RGFP966 might reduce HDAC3 expression and HDAC3 activities, and then eosinophils and mast cells recruitment, goblet cells proliferation and inflammatory cytokines levels are decreased, resulting in the alleviation of allergic and inflammatory responses in AR mice.