Callicarpa japonica Thunb. ameliorates allergic airway inflammation by suppressing NF-κB activation and upregulating HO-1 expression

Regional variations in allergen-induced airway inflammation correspond to changes in soluble guanylyl cyclase heme and expression of heme oxygenase-1

Asthma is characterized by airway remodeling and hyperreactivity. Our earlier studies determined that the nitric oxide (NO)-soluble guanylyl cyclase (sGC)-cGMP pathway plays a significant role in human lung bronchodilation. However, this bronchodilation is dysfunctional in asthma due to high NO levels, which cause sGC to become heme-free and desensitized to its natural activator, NO. In order to determine how asthma impacts the various lung segments/lobes, we mapped the inflammatory regions of lungs to determine whether such regions coincided with molecular signatures of sGC dysfunction. We demonstrate using murine models of asthma (OVA and CFA/HDM) that the inflamed segments of these murine lungs can be tracked by upregulated expression of HO1 and these regions in turn overlap with regions of heme-free sGC as evidenced by a decreased sGC-α1β1 heterodimer and an increased response to heme-independent sGC activator, BAY 60-2770, relative to naïve uninflamed regions. We also find that NO generated from iNOS upregulation in the inflamed segments has a higher impact on developing heme-free sGC as increasing iNOS activity correlates linearly with elevated heme-independent sGC activation. This excess NO works by affecting the epithelial lung hemoglobin (Hb) to become heme-free in asthma, thereby causing the Hb to lose its NO scavenging function and exposing the underlying smooth muscle sGC to excess NO, which in turn becomes heme-free. Recognition of these specific lung segments enhances our understanding of the inflamed lungs in asthma with the ultimate aim to evaluate potential therapies and suggest that regional and not global inflammation impacts lung function in asthma.

Unveiling the potent effect of vitamin D: harnessing Nrf2/HO-1 signaling pathways as molecular targets to alleviate urban particulate matter-induced asthma inflammation

BACKGROUND

Asthma is the most common allergic disease characterized by an inflammatory response in the airways. Mechanismly, urban particulate matter (PM) is the most widely air pollutant associated with increased asthma morbidity and airway inflammation. Current research found that vitamin D is an essential vitamin with anti-inflammatory, antioxidant and other medical efficacy. Inadequate or deficient vitamin D often leads to the pathogenesis and stability of asthma. NGF exacerbates airway inflammation in asthma by promoting smooth muscle cell proliferation and inducing the Th2 immune response. Activation of the Nrf2/HO-1 signaling pathway can exert a protective effect on the inflammatory response in bronchial asthma. However, the specific mechanism of this pathway in PM-involved asthmatic airway smooth muscle cells remains unclear.

METHODS

Mice were sensitized and challenged with Ovalbumin (OVA) to establish an asthma model. They were then exposed to either PM, vitamin D or a combination of both, and inflammatory responses were observed. Including, acetylcholine stimulation at different concentrations measured airway hyperresponsiveness in mice. Bronchoalveolar lavage fluid (BALF) and serum were collected for TNF-α, IL-1β, IL-6, and Nerve growth factor (NGF) analysis. Additionally, lung tissues underwent histopathological examination to observe alveolar structure and inflammatory cell infiltration. Specific ELISA kits were utilized to determine the levels of the inflammatory factors TNF-α, IL-1β, IL-6, and Nerve growth factor (NGF). Nrf2/HO-1 signaling pathways were examined by western blot analysis. Meanwhile, we constructed a cell system with low HO-1 expression by lentiviral transfection of airway smooth muscle cells. The changes of Nrf2, HO-1, and NGF were observed after the treatment of OVA, PM, and Vit D were given.

RESULTS

The in vivo results showed that vitamin D significantly alleviated pathological changes in lung tissue of PM-exposed mice models. Mechanismly, vitamin D decreased substantial inflammatory cell infiltration in lung tissue, as well as the number of inflammatory cells in BALF. Furthermore, vitamin D reduced the heightened inflammatory factors including of TNF-α, IL-1β, IL-6, and NGF caused by PM exposure, and triggered the activity of nucleus Nrf2 and HO-1 in PM-exposed asthmatic mice. Notably, knockdown HO-1 weakens the Vitamin D- mediated inhibition to pollution toxicity in asthma. Importantly, in vitro experiments on OVA-stimulated mice airway smooth muscle cells, the results showed that OVA and PM, respectively, reduced Nrf2/HO-1 and increased NGF's expression, while vitamin D reversed the process. And in the HO-1 knockdown cell line of Lenti-si-HO-1 ASMCs, OVA and PM reduced Nrf2's expression, while HO-1 and NGF's expression were unchanged.

CONCLUSIONS

The above results demastrate that vitamin D downregulated the inflammatory response and the expression of NGF by regulating the Nrf2/HO-1 signaling pathways in airway smooth muscle cells, thereby showing potent anti-inflammatory activity in asthma.

Aromadendrin inhibits PMA-induced cytokine formation/NF-κB activation in A549 cells and ovalbumin-induced bronchial inflammation in mice

Hyperproduction of immune cell-derived inflammatory molecules and recruitment of immune cells promote the development of allergic asthma (AA). Aromadendrin (ARO) has various biological properties including anti-inflammatory effects. In this study, we evaluated the ameliorative effects of ARO on the development of AA in vitro and in vivo. Phorbol 12-myristate 13-acetate (PMA, 100 nM) was used to induce inflammation in A549 airway epithelial cells. The cohesion of A549 and eosinophil EOL-1 cells was studied. Ovalbumin (30 or 60 μg)/Alum (3 mg) mixture was adapted for AA induction in mice. ARO (5 or 10 mg/kg, p. o.) was administered to mice to investigate its ameliorative effect on AA development. Enzyme-linked immunosorbent assay, western blotting, and hematoxylin and eosin/periodic acid Schiff staining were performed to study the ameliorative effect of ARO on bronchial inflammation. In PMA-stimulated A549 cells, the upregulation of cytokines (interleukin [IL]-1β/IL-6/tumor necrosis factor alpha [TNF-α]/monocyte chemoattractant protein [MCP]-1]) and nuclear factor kappa B (NF-κB) activation was effectively reduced by ARO pretreatment. ARO suppressed the adhesion of A549 cells and eosinophils. In ovalbumin-induced AA mice, the levels of cells, such as eosinophils, Th2 cytokines, MCP-1 in bronchoalveolar lavage fluid, IgE in serum, and inducible nitric oxide synthase/cyclooxygenase-2 expression in the lung tissue were upregulated, which were all suppressed by ARO. In addition, the increase in cell inflow and mucus formation in the lungs of AA mice was reversed by ARO as per histological analysis. ARO also modulated NF-κB activation in the lungs of AA mice. Overall, the anti-inflammatory properties of ARO in vitro/in vivo studies of AA were notable. Thus, ARO has a modulatory effect on bronchial inflammation and may be a potential adjuvant for AA treatment.

Black Ginseng Extract Exerts Potentially Anti-Asthmatic Activity by Inhibiting the Protein Kinase Cθ-Mediated IL-4/STAT6 Signaling Pathway

Asthma is a chronic inflammatory lung disease that causes respiratory difficulties. Black ginseng extract (BGE) has preventative effects on respiratory inflammatory diseases such as asthma. However, the pharmacological mechanisms behind the anti-asthmatic activity of BGE remain unknown. To investigate the anti-asthmatic mechanism of BGE, phorbol 12-myristate 13-acetate plus ionomycin (PMA/Iono)-stimulated mouse EL4 cells and ovalbumin (OVA)-induced mice with allergic airway inflammation were used. Immune cells (eosinophils/macrophages), interleukin (IL)-4, -5, -13, and serum immunoglobulin E (IgE) levels were measured using an enzyme-linked immunosorbent assay. Inflammatory cell recruitment and mucus secretion in the lung tissue were estimated. Protein expression was analyzed via Western blotting, including that of inducible nitric oxide synthase (iNOS) and the activation of protein kinase C theta (PKCθ) and its downstream signaling molecules. BGE decreased T helper (Th)2 cytokines, serum IgE, mucus secretion, and iNOS expression in mice with allergic airway inflammation, thereby providing a protective effect. Moreover, BGE and its major ginsenosides inhibited the production of Th2 cytokines in PMA/Iono-stimulated EL4 cells. In EL4 cells, these outcomes were accompanied by the inactivation of PKCθ and its downstream transcription factors, such as nuclear factor of activated T cells (NFAT), nuclear factor kappa B (NF-κB), activator of transcription 6 (STAT6), and GATA binding protein 3 (GATA3), which are involved in allergic airway inflammation. BGE also inhibited the activation of PKCθ and the abovementioned transcriptional factors in the lung tissue of mice with allergic airway inflammation. These results highlight the potential of BGE as a useful therapeutic and preventative agent for allergic airway inflammatory diseases such as allergic asthma.

Electroacupuncture-induced activation of GABAergic system alleviates airway inflammation in asthma model by suppressing TLR4/MyD88/NF-κB signaling pathway

BACKGROUND

Electroacupuncture (EA) has been shown to attenuate airway inflammation in asthmatic mice; however, the underlying mechanism is not fully understood. Studies have shown that EA can significantly increase the inhibitory neurotransmitter γ-aminobutyric acid (GABA) content in mice, and can also increase the expression level of GABA type A receptor (GABAAR). Furthermore, activating GABAAR may relieve inflammation in asthma by suppressing toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-kappa B (NF-κB) signaling pathway. Therefore, this study aimed to investigate the role of GABAergic system and TLR4/MyD88/NF-κB signaling pathway in asthmatic mice treated with EA.

METHODS

A mouse model of asthma was established, and a series of methods including Western blot and histological staining assessment were employed to detect the level of GABA, and expressions of GABAAR and TLR4/MyD88/NF-κB in lung tissue. In addition, GABAAR antagonist was used to further validate the role and mechanism of GABAergic system in mediating the therapeutic effect of EA in asthma.

RESULTS

The mouse model of asthma was established successfully, and EA was verified to alleviate airway inflammation in asthmatic mice. The release of GABA and the expression of GABAAR were significantly increased in asthmatic mice treated with EA compared with untreated asthmatic mice ( P  < 0.01), and the TLR4/MyD88/NF-κB signaling pathway was down-regulated. Moreover, inhibition of GABAAR attenuated the beneficial effects of EA in asthma, including the regulation of airway resistance and inflammation, as well as the inhibitory effects on TLR4/MyD88/NF-κB signaling pathway.

CONCLUSION

Our findings suggest that GABAergic system may be involved in mediating the therapeutic effect of EA in asthma, possibly by suppressing the TLR4/MyD88/NF-κB signaling pathway.

Leonurine attenuates OVA-induced asthma via p38 MAPK/NF-κB signaling pathway

Leonurine (Leo) is a natural alkaloid extracted from Herba leonuri, which has many biological activities. However, whether leonurine has a protective effect on asthma remains unknown. The purpose of this study was to investigate the protective effect of leonurine on asthma. We evaluated its therapeutic effect and related signal transduction in LPS-induced RAW264.7 cells and OVA-induced asthmatic mice. In addition, we used network pharmacology, molecular docking and molecular dynamics simulation to verify the experimental results. In LPS-induced RAW 264.7 cells, leonurine significantly reduced the production of TNF-α and IL-6, andinhibited the activation of p38 MAPK/NF-κB signaling pathway. In OVA-induced asthmatic mice, leonurine decreased the number of inflammatory cells in the bronchoalveolar lavage fluid (BALF), particularly neutrophils and eosinophils. Leonurine also reduced the contents of IL-4, IL-5, IL-13 in the BALF and OVA-IgE in the serum. Leonurine remarkly improved OVA-induced inflammatory cell infiltration and significantly inhibited mucus overproduction. In addition, leonurine inhibited the activation of p38 MAPK/NF-κB signaling pathway in the lung tissues of asthmatic mice. Network pharmacology suggested that p38 MAPKα was a potential target of leonurine in the treatment of asthma. Molecular docking and molecular dynamics simulations indicated that leonurine could stably bind to p38 MAPKα protein. In summary, leonurine attenuated asthma by regulating p38 MAPK/NF-κB signaling pathway.

Methyl P-Coumarate Ameliorates the Inflammatory Response in Activated-Airway Epithelial Cells and Mice with Allergic Asthma

Methyl p-coumarate (methyl p-hydroxycinnamate) (MH) is a natural compound found in a variety of plants. In the present study, we evaluated the ameliorative effects of MH on airway inflammation in an experimental model of allergic asthma (AA). In this in vitro study, MH was found to exert anti-inflammatory activity on PMA-stimulated A549 airway epithelial cells by suppressing the secretion of IL-6, IL-8, MCP-1, and ICAM-1. In addition, MH exerted an inhibitory effect not only on NF-κB (p-NF-κB and p-IκB) and AP-1 (p-c-Fos and p-c-Jun) activation but also on A549 cell and EOL-1 cell (eosinophil cell lines) adhesion. In LPS-stimulated RAW264.7 macrophages, MH had an inhibitory effect on TNF-α, IL-1β, IL-6, and MCP-1. The results from in vivo study revealed that the increases in eosinophils/Th2 cytokines/MCP-1 in the bronchoalveolar lavage fluid (BALF) and IgE in the serum of OVA-induced mice with AA were effectively inhibited by MH administration. MH also exerted a reductive effect on the immune cell influx, mucus secretion, and iNOS/COX-2 expression in the lungs of mice with AA. The effects of MH were accompanied by the inactivation of NF-κB. Collectively, the findings of the present study indicated that MH attenuates airway inflammation in mice with AA, suggesting its potential as an adjuvant in asthma therapy.

Allantoin Inhibits Compound 48/80-Induced Pseudoallergic Reactions In Vitro and In Vivo

Pseudoallergic reactions are hypersensitivity reactions mediated by an IgE-independent mechanism. Since allantoin (AT)-mediated pseudoallergy has not been studied, in this study, our objective is to investigate the anti-pseudoallergy effect of AT and its underlying mechanism. In vitro, β-hexosaminidase (β-Hex) and histamine (HIS) release assays, inflammatory cytokine assays, toluidine blue staining, and F-actin microfilament staining were used to evaluate the inhibitory effect of AT in RBL-2H3 cells stimulated with Compound 48/80 (C48/80). Western blot analysis is further performed to investigate intracellular calcium fluctuation-related signaling pathways. In vivo, Evans Blue extraction, paw swelling, and the diameter of Evans Blue extravasation were evaluated, and skin tissues are examined for histopathological examination in mice with passive cutaneous anaphylaxis (PCA) induced by C48/80. Body temperature is measured, and the levels of cytokines are further determined by ELISA kits in mice with active systemic anaphylaxis (ASA) induced by C48/80. The results show that AT dose-dependently inhibited degranulation in C48/80-stimulated RBL-2H3 cells by inhibiting β-Hex and HIS release, reducing the levels of TNF-α, IL-8, and MCP-1, inhibiting shape changes due to degranulation and disassembling the F-actin cytoskeleton. Furthermore, AT dose-dependently inhibits the phosphorylation of PLCγ and IP3R. In vivo, AT decreased Evans Blue extravasation, paw swelling, and the diameter of Evans Blue extravasation and significantly ameliorate pathological changes and mast cell degranulation in C48/80-induced PCA. Furthermore, AT help the mice recover from the C48/80-induced decrease in body temperature and decreased the levels of cytokines in C48/80-treated ASA mice. Our results indicate that allantoin inhibits compound 48/80-induced pseudoallergic reactions. AT has the potential to be used in IgE-independent anti-allergic and anti-inflammatory therapies.

Acute iron oxide nanoparticles exposure induced murine eosinophilic airway inflammation via TLR2 and TLR4 signaling

Iron oxide nanoparticles (Fe₂ O₃ NPs) is the main component of air pollution particles in urban rail transit environment. People are more exposed to Fe₂ O₃ NPs, however, the studies on relationship between Fe₂ O₃ NPs and respiratory health are limited. In the present study, acute airway inflammation caused by Fe₂ O₃ NPs and its possible mechanism were investigated. BALB/c mice were intratracheally challenged with different concentrations of Fe₂ O₃ NPs. Fe₂ O₃ NPs induced bronchial epithelial barrier function damage, infiltration of neutrophils and lymphocytes into the airway submucosa, secretion of mucus in the airway epithelium and elevated expression of eosinophil major basic protein (EMBP) in lungs. Compared with the control group, Fe₂ O₃ NPs increased eosinophils by 20 times in bronchoalveolar lavage fluid (BALF), and markedly increased eosinophils related cytokines and chemokines, including interleukin (IL) -5, IL-33, thymic stromal lymphopoietin (TSLP), monocyte chemotactic protein (MCP)-3, eotaxin, tumor necrosis factor (TNF)-α, keratinocyte chemoattractant (KC). Furthermore, Fe₂ O₃ NPs up-regulated levels of IL-5, MCP-3, eotaxin, and KC in serum. In vitro studies showed that Fe₂ O₃ NPs increased the genes and proteins expression of Toll-like receptors (TLR)-2, TLR4, TNF receptor associated factor 6 (TRAF6), myeloid differentiation factor 88 (MyD88), nuclear factor (NF)-κB, and TNF-α in RAW267.4 cells. The downstream inflammatory cytokine protein expression and release such as TNF-α was significantly decreased after using TLR2/TLR4 inhibitor OxPAPC, but not MyD88 inhibitor ST2825. These results suggest that TLR2 and TLR4 played important role in Fe₂ O₃ NPs inducing acute eosinophilic airway inflammation in the murine lung.

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.

Lagerstroemia ovalifolia Exerts Anti- Inflammatory Effects in Mice of LPSInduced ALI via Downregulating of MAPK and NF-κB Activation

Lagerstroemia ovalifolia Teijsm. & Binn. (LO) (crape myrtle) has reportedly been used as traditional herbal medicine (THM) in Java, Indonesia. Our previous study revealed that the LO leaf extract (LOLE) exerted anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Based on this finding, the current study aimed to evaluate the protective effects of LOLE in a mouse model of LPS-induced acute lung injury (ALI). The results showed that treatment with LPS enhanced the inflammatory cell influx into the lungs and increased the number of macrophages and the secretion of the inflammatory cytokines in the bronchoalveolar lavage fluid (BALF) of mice. However, these effects were notably abrogated with LOLE pretreatment. Furthermore, the increase of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and monocyte chemoattractant protein-1 (MCP-1) expression in the lung tissues of mice with ALI was also reversed by LOLE. In addition, LOLE significantly suppressed the LPS-induced activation of the MAPK/NF-κB signaling pathway and led to heme oxygenase-1 (HO-1) induction in the lungs. Additionally, in vitro experiments showed that LOLE enhanced the expression of HO-1 in RAW264.7 macrophages. The aforementioned findings collectively indicate that LOLE exerts an ameliorative effect on inflammatory response in the airway of ALI mice.

Effect of Yijin-Tang, an Oriental Traditional Formula, on Allergic Responses Using an Ovalbumin-Induced Murine Asthma Model

Yijin-tang is an oriental traditional herb used to treat inflammatory diseases. In the present study, we investigated the protective effects of Yijin-tang water extract (YTE) using an ovalbumin- (OVA-) induced asthma model, focusing on the antioxidant and anti-inflammatory properties of the herb. BALB/c mice were intraperitoneally injected with OVA on days 0 and 14 and then challenged with OVA on days 21, 22, and 23. The animals were orally administered YTE (200 and 400 mg/kg) from days 18 to 23, and this was found to significantly decrease airway hyperresponsiveness and release of inflammatory cells, cytokines, and OVA-specific immunoglobulin E in mice with asthma. In addition, YTE was associated with a marked reduction in airway inflammation and mucus production in lung tissue of mice with asthma. Furthermore, YTE suppressed the expression of matrix metalloproteinase-9 and phosphorylation of ERK in the lungs, which in turn led to a reduction in inducible nitric oxide synthases and an elevation in reduced glutathione and heme oxygenase-1. In conclusion, YTE effectively suppressed allergic responses in mice with asthma and the effect was closely related to antioxidant and anti-inflammatory properties of the herb. Our results indicate that YTE may be a potential agent for the treatment of allergic asthma.

The Role of Macrophages in the Development of Acute and Chronic Inflammatory Lung Diseases

Macrophages play an important role in the innate and adaptive immune responses of organ systems, including the lungs, to particles and pathogens. Cumulative results show that macrophages contribute to the development and progression of acute or chronic inflammatory responses through the secretion of inflammatory cytokines/chemokines and the activation of transcription factors in the pathogenesis of inflammatory lung diseases, such as acute lung injury (ALI), acute respiratory distress syndrome (ARDS), ARDS related to COVID-19 (coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)), allergic asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). This review summarizes the functions of macrophages and their associated underlying mechanisms in the development of ALI, ARDS, COVID-19-related ARDS, allergic asthma, COPD, and IPF and briefly introduces the acute and chronic experimental animal models. Thus, this review suggests an effective therapeutic approach that focuses on the regulation of macrophage function in the context of inflammatory lung diseases.