Anti-Inflammatory Effects of Mitogen-Activated Protein Kinase Kinase Inhibitor U0126 in an Asthma Mouse Model

Dilodendron bipinnatum Radlk. ameliorates airway inflammation through multiple targets in a murine model of ovalbumin-induced allergic airway disease

ETHNOPHARMACOLOGICAL RELEVANCE

Dilodendron bipinnatum Radlk., Sapindaceae, a tree of the Mato Grosso Pantanal, is popularly known as "mulher-pobre". The decoction or infusion of its inner stem bark is used for treating inflammatory conditions.

AIM OF THE STUDY

To determine if a 70% hydroethanolic extract of Dilodendron bipinnatum stem bark (HEDb) is able to reduce allergic airway inflammation in a murine model of ovalbumin (OVA)-induced allergic asthma.

MATERIAL AND METHODS

The inner stem bark powder was macerated in a 70% hydroethanolic solution (1:3 w/v) to obtain HEDb. The induction of experimental asthma was accomplished as follows: on days 1 and 10, Swiss mice were sensitized by an intraperitoneal injection of OVA (100 µg/mL) and aluminum hydroxide (10 µg/mL). From day 19 to 24, animals (n = 6/per group) were treated (p.o.) twice a day with either vehicle (distilled water), HEDb (20, 100 and 500 mg/kg) or dexamethasone (0.5 mg/kg). Sham group animals were intraperitoneally injected and challenged with saline solution (0.9%) instead of OVA and received distilled water orally instead of HEDb, whereas the other groups were challenged with OVA (3% in saline) by aerosolization. On day 25, bronchoalveolar lavage fluid (BALF) was collected for the quantification of total leukocytes, neutrophils, eosinophils, mononuclear cells and Th2 cytokines (IL-4, IL-5, and IL-13). The lungs were collected for histopathological analysis and blood was assayed to determine serum IgE levels. The anti-inflammatory activity of HEDb was additionally confirmed by a lipoxygenase (LO) inhibitory assay in vitro.

RESULTS

Compared to the sham group, the OVA group showed significantly greater numbers of total leukocytes, neutrophils, eosinophils, and mononuclear cells, as well as inflammatory cytokines in BALF, and also IgE in the serum. HEDb treated mice showed a significant decrease in inflammatory cell accumulation in BALF, with the maximum response observed at 500 mg/kg. Furthermore, the levels of IL-4, IL-5 and IL-13 in BALF, and of IgE in serum, were also considerably reduced as compared to the OVA group. The histopathological examination of the lungs of mice in the vehicle group showed a significant increase in hemorrhagic damage, mucus, perivascular and peribronchial inflammatory cell infiltrates, as well as mast cell degranulation compared to sham. HEDb (100 and 500 mg/kg) remarkably decreased all these parameters, presenting at the highest dose an anti-inflammatory effect comparable to that of dexamethasone (0.5 mg/kg). HEDb also had notable direct anti-inflammatory properties demonstrated by the inhibition of 15-LO activity in vitro (IC₅₀ = 1.0-5.0 µg/mL).

CONCLUSIONS

These results somewhat agree on the popular use of the inner stem bark of D. bipinnatum as a treatment for allergic asthma. The HEDb exhibits significant anti-inflammatory activity in the OVA-induced mouse model of allergic asthma, possibly due to the down-regulation of the Th2 responses and LO inhibition, resulting in improvements in all analyzed inflammatory parameters.

Involvement of the annexin A1-Fpr anti-inflammatory system in the ocular allergy

Annexin A1 (ANXA1)-formyl peptide receptor (Fpr) system is potent effective mediators in the control of the inflammatory response. In this study, we evaluate the potential involvement of the Fpr family in the protective effect of the mimetic peptide of ANXA1 (ANXA1_2-26) using an experimental allergic conjunctivitis (AC) model in mice. Ovalbumin (OVA)/Alum-immunized wild-type (WT) and ANXA1-null (ANXA1^-/-) Balb/c mice (days 0 and 7) were challenged by eye drops containing OVA on days 14-16, and two groups received ANXA1_2-26 alone or with Fpr antagonist Boc2 intraperitoneally during challenged days. As expected, plasma IgE anti-OVA levels increased significantly in the OVA-immunized WT and ANXA1^-/- mice, supporting the efficacy of AC model. AC increased Fpr1 and Fpr2 levels in the conjunctiva and the lack of endogenous ANXA1 exacerbated Fpr2 expression only. In contrast, administering ANXA1_2-26 in the WT mice diminished Fpr2 levels in the conjunctiva, and the effect was reverted by Boc2. Ultrastructural analysis showed the co-localization of Fpr2 and ANXA1 in the plasma membrane of mast cells (MCs), eosinophils and neutrophils, supporting this system as being operative in the AC. Boc2 abrogated the ANXA1_2-26 effect by increasing the MC degranulation and the eosinophil influx in the conjunctiva, and these findings were supported by peroxidase eosinophil, eotaxin and MC protease levels. Additionally, the ANXA1_2-26-Fpr system in the AC was associated with the activation of ERK and JNK. Collectively, the data provided in vivo supports the anti-allergic effects of the ANXA1-Fpr system and may serve as a therapeutic target in this ocular disorder.

Suppressive Effect of 4-Hydroxy-2-(4-Hydroxyphenethyl) Isoindoline-1,3-Dione on Ovalbumin-Induced Allergic Asthma

4-Hydroxy-2-(4-hydroxyphenethyl)isoindoline-1,3-dione (PD1) is a synthetic phthalimide derivative of a marine compound. PD1 has peroxisome proliferator-activated receptor (PPAR) γ agonistic and anti-inflammatory effects. This study aimed to investigate the effect of PD1 on allergic asthma using rat basophilic leukemia (RBL)-2H3 mast cells and an ovalbumin (OVA)-induced asthma mouse model. In vitro, PD1 suppressed β-hexosaminidase activity in RBL-2H3 cells. In the OVA-induced allergic asthma mouse model, increased inflammatory cells and elevated Th2 and Th1 cytokine levels were observed in bronchoalveolar lavage fluid (BALF) and lung tissue. PD1 administration decreased the numbers of inflammatory cells, especially eosinophils, and reduced the mRNA and protein levels of the Th2 cytokines including interleukin (IL)-4 and IL-13, in BALF and lung tissue. The severity of inflammation and mucin secretion in the lungs of PD1-treated mice was also less. These findings indicate that PD1 could be a potential compound for anti-allergic therapy.

Hydroxypropyltrimethyl ammonium chloride chitosan activates RAW 264.7 macrophages through the MAPK and JAK-STAT signaling pathways

Hydroxypropyltrimethyl ammonium chloride chitosan (HACC) is a water-soluble derivative of chitosan. To investigate the immunostimulatory effects of HACC, quaternized chitosans with different molecular weights were prepared and their effects on RAW 264.7 macrophages were compared. The results showed that HACC promoted nitric oxide (NO) production in a molecular weight- and dose-dependent manner. Lower molecular weight HACC was more active in promoting NO production. Furthermore, flow cytometry analysis showed that HACC significantly promoted the production of interleukin-6 and tumor necrosis factor-α. These results were further demonstrated by quantitive real-time reverse transcription polymerase chain reaction and western blot analysis. Moreover, western blotting revealed that HACC induced the phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38, and signal transducer and activator of transcription (STAT) proteins. In conclusion, HACC activated RAW 264.7 cells through the mitogen-activated protein kinases and Janus kinase/STAT pathways.

Protection by mTOR Inhibition on Zymosan-Induced Systemic Inflammatory Response and Oxidative/Nitrosative Stress: Contribution of mTOR/MEK1/ERK1/2/IKKβ/IκB-α/NF-κB Signalling Pathway

Mammalian target of rapamycin (mTOR), a serine/threonine kinase regulate variety of cellular functions including cell growth, differentiation, cell survival, metabolism, and stress response, is now appreciated to be a central regulator of immune responses. Because mTOR inhibitors enhanced the anti-inflammatory activities of regulatory T cells and decreased the production of proinflammatory cytokines by macrophages, mTOR has been a pharmacological target for inflammatory diseases. In this study, we examined the role of mTOR in the production of proinflammatory and vasodilator mediators in zymosan-induced non-septic shock model in rats. To elucidate the mechanism by which mTOR contributes to non-septic shock, we have examined the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system caused by mTOR/mitogen-activated protein kinase kinase (MEK1)/extracellular signal-regulated kinase (ERK1/2)/inhibitor κB kinase (IKKβ)/inhibitor of κB (IκB-α)/nuclear factor-κB (NF-κB) signalling pathway activation. After 1 h of zymosan (500 mg/kg, i.p.) administration to rats, mean arterial blood pressure (MAP) was decreased and heart rate (HR) was increased. These changes were associated with increased expression and/or activities of ribosomal protein S6, MEK1, ERK1/2, IKKβ, IκB-α and NF-κB p65, and NADPH oxidase system activity in cardiovascular and renal tissues. Rapamycin (1 mg/kg, i.p.), a selective mTOR inhibitor, reversed these zymosan-induced changes in these tissues. These observations suggest that activation of mTOR/MEK1/ERK1/2/IKKβ/IκB-α/NF-κB signalling pathway with proinflammatory and vasodilator mediator formation and NADPH oxidase system activity contributes to systemic inflammation in zymosan-induced non-septic shock. Thus, mTOR may be an optimal target for the treatment of the diseases characterized by the severe systemic inflammatory response.

Methylation status of ORMDL3 regulates cytokine production and p-ERK/MMP9 pathway expression

Orosomucoid like-3 (ORMDL3) has been identified to be associated with the development of asthma according to previous studies. However, the definite role of ORMDL3 in the pathogenesis of asthma remains unclear. In this study, we found ORMDL3 was highly expressed in PBMC specimens from childhood asthma patients. Cytokines production and p-ERK/MMP-9 pathway expression was also increased in childhood asthma patients compared with controls. In addition, ORMDL3 overexpression induced IL-6 and IL-8 release and activated p-ERK/MMP-9 pathway in vitro. Increased ORMDL3 expression was observed after treated with 5-Aza-CdR. 5-Aza-CdR decreased the percentage of the CpG island in the ORMDL3 promoter region and increased its promoter activity. In addition, 5-Aza-CdR significantly increased IL-6 and IL-8 levels in NHBE cells while there was no obvious alteration after knocking down ORMDL3. Knockdown of ORMDL3 also significantly decreased the expression of p-ERK/MMP-9 pathway in the presence or absence of 5-Aza-CdR. In conclusion, our study provided novel evidence for the association between ORMDL3 and asthma-associated cytokines. Moreover, DNA methylation plays an important role in ORMDL3-mediated increased IL-6 and IL-8 levels and p-ERK/MMP-9 pathway expression.

Influence of rutin on the effects of neonatal cigarette smoke exposure-induced exacerbated MMP-9 expression, Th17 cytokines and NF-κB/iNOS-mediated inflammatory responses in asthmatic mice model

Allergic asthma is one of the most enduring diseases of the airway. The T-helper cells and regulatory T-cells are critically involved in inflammatory responses, mucus hypersecretion, airway remodelling and in airway hyper-responsiveness. Cigarette smoke (CS) has been found to aggravate inflammatory responses in asthma. Though currently employed drugs are effective, associated side effects demand identification and development of novel drugs with negligible or no adverse effects. Rutin, plant-derived flavonoid has been found to possess antioxidant and anti-inflammatory effects. We investigated the ability of rutin to modulate T-cells and inhibit inflammation in experimentally-induced asthma in cigarette smoke exposed mice. Separate groups of neonatal mice were exposed to CS for 10 days from post-natal days 2 to 11. After 2 weeks, the mice were sensitized and challenged with ovalbumin (OVA). Treatment group were given rutin (37.5 or 75 mg/kg body weight) during OVA sensitization and challenge. Rutin treatment was found to significantly inhibit cellular infiltration in the airways and Th2 and Th17 cytokine levels as well. Flow cytometry revealed effectively raised CD4⁺CD25⁺Fox3⁺ Treg cells and supressed Th17 cell population on rutin treatment. Airway hyper-responsiveness observed following CS and OVA challenge were inhibited by rutin. NF-κB and iNOS, chief regulators of inflammatory responses robustly activated by CS and OVA were down-regulated by rutin. Rutin also inhibited the expression of matrix metalloproteinase 9, thereby aiding in prevention of airway remodelling in asthma thereby revealing to be a potent candidate in asthma therapy.

FABP4 regulates eosinophil recruitment and activation in allergic airway inflammation

Fatty acid binding protein 4 (FABP4), a member of a family of lipid-binding proteins, is known to play a role in inflammation by virtue of its ability to regulate intracellular events such as lipid fluxes and signaling. Studies have indicated a proinflammatory role for FABP4 in allergic asthma although its expression and function in eosinophils, the predominant inflammatory cells recruited to allergic airways, were not investigated. We examined expression of FABP4 in murine eosinophils and its role in regulating cell recruitment in vitro as well as in cockroach antigen (CRA)-induced allergic airway inflammation. CRA exposure led to airway recruitment of FABP4-expressing inflammatory cells, specifically eosinophils, in wild-type (WT) mice. FABP4 expression in eosinophils was induced by TNF-α as well as IL-4 and IL-13. FABP4-deficient eosinophils exhibited markedly decreased cell spreading/formation of leading edges on vascular cell adhesion molecule-1 and significantly decreased adhesion to intercellular adhesion molecule-1 associated with reduced β2-integrin expression relative to WT cells. Furthermore, FABP4-deficient eosinophils exhibited decreased migration, F-actin polymerization, calcium flux, and ERK(1/2) phosphorylation in response to eotaxin-1. In vivo, CRA-challenged FABP4-deficient mice exhibited attenuated eosinophilia and significantly reduced airway inflammation (improved airway reactivity, lower IL-5, IL-13, TNF-α, and cysteinyl leukotriene C4 levels, decreased airway structural changes) compared with WT mice. In conclusion, expression of FABP4 in eosinophils is induced during conditions of inflammation and plays a proinflammatory role in the development of allergic asthma by promoting eosinophil adhesion and migration and contributing to the development of various aspects of airway inflammation.

Regulatory role of heme oxygenase-1 in silica-induced lung injury

Background

Silicosis, a progressive inflammatory lung disease attributed mainly to occupational exposure to silica dust, shows loss of lung function even after cessation of exposure. In addition to conventional evaluation methods such as chest X-ray, computed tomography, and spirometry, we identified heme oxygenase (HO)-1, an inducible antioxidant, as a potential biomarker to identify at-risk patients. We found that HO-1 was critical in attenuating the disease progression of silicosis; however, the key signaling pathway has not yet been elucidated. Here, we report the critical pathway after silica exposure, focusing on the role of silica-derived reactive oxygen species (ROS) signaling and its attenuation, which is mediated by HO-1 induction, in vivo and in vitro.

Methods

Normal bronchial epithelial cells and a macrophage cell line, as well as a murine silicosis model generated by intratracheal administration of 2.5 mg of crystalline silica, were used in this study. The pathways activated in response to silica exposure, including the mitogen-activated protein kinase (MAPK) signaling pathway, were examined and compared with or without super-induction of HO-1.

Results

The murine silicosis model was first assessed for the evaluation of activated pathways after silica exposure, focusing on ROS-MAPK activation. In the murine model, increased expression of HO-1 in the lungs was observed after silica-instillation. Moreover, silica-medicated activation of extracellular signal-regulated kinase (ERK) in the lungs was attenuated in response to silica-induced HO-1 upregulation. Activation of other MAPKs, such as p38 and c-Jun N-terminal kinase pathways, after silica exposure was not significantly different irrespective of HO-1 induction. Further in vitro studies showed that 1) silica-induced HO-1 was significantly attenuated by inhibiting ERK activation, and 2) carbon monoxide and bilirubin as final byproducts of HO-1 could inhibit ERK activation. Taken together, silica-induced HO-1 upregulation was mediated by ERK activation, and HO-1 further regulates ERK activation via its final byproducts, carbon monoxide and bilirubin.

Conclusions

This is the first study to demonstrate the regulatory role of HO-1 in silicosis. This finding could contribute to the development of a treatment strategy of monitoring HO-1 levels as a marker of therapeutic intervention.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0852-6) contains supplementary material, which is available to authorized users.

Regulation of eosinophil recruitment and allergic airway inflammation by heparan sulfate proteoglycan (HSPG) modifying enzymes

BACKGROUND

HSPGs are glycoproteins containing covalently attached heparan sulfate (HS) chains which bind to growth factors, chemokines, etc., and regulate various aspects of inflammation including cell recruitment. We previously showed that deletion of endothelial N-acetylglucosamine N-deacetylase-N-sulfotransferase-1 (Ndst1), an enzyme responsible for N-sulfation during HS biosynthesis, reduces allergic airway inflammation (AAI). Here, we investigated the importance of O-sulfation mediated by uronyl 2-O-sulfotransferase (Hs2st) in development of AAI relative to N-sulfation.

METHODS

Mice deficient in endothelial and leukocyte Hs2st (Hs2st^f/fTie2Cre⁺) or Ndst1 (Ndst1^f/fTie2Cre⁺) and WT mice were challenged with Alternaria alternata and evaluated for airway inflammation. Trafficking of murine eosinophils on lung endothelial cells was examined in vitro under conditions of flow.

RESULTS

Exposure to Alternaria decreased expression level of Hs2st in WT mice while level of Ndst1 remained unchanged. Compared to WT mice, Alternaria-challenged Hs2st^f/fTie2Cre⁺ mice exhibited significantly increased eosinophils in the bone marrow, bronchoalveolar lavage fluid [BALF] and lung tissue associated with persistent airway hyperresponsiveness, airway mucus hypersecretion and elevated Th2 cytokines. In contrast, Alternaria-challenged Ndst1^f/fTie2Cre⁺ mice exhibited a marked reduction in airway eosinophilia, mucus secretion and smooth muscle mass compared to WT counterparts. While BALF eotaxins were lower in Alternaria-challenged Hs2st^f/fTie2Cre⁺ relative to WT mice, they were not reduced to background levels as in allergen-challenged Ndst1^f/fTie2Cre⁺ mice. Trafficking of murine eosinophils under conditions of flow in vitro was similar on Hs2st-deficient and WT endothelial cells. Expression of ZO-1 in Hs2st-deficient lung blood vessels in control and allergen-challenged mice was significantly lower than in WT counterparts.

CONCLUSIONS

Our study demonstrates that allergen exposure reduces expression of Hs2st; loss of uronyl 2-O-sulfation in endothelial and leukocyte HSPG amplifies recruitment of eosinophils likely due to a compromised vascular endothelium resulting in persistent inflammation whereas loss of N-sulfation limits eosinophilia and attenuates inflammation underscoring the importance of site-specific sulfation in HSPG to their role in AAI.

Differential Inflammatory-Response Kinetics of Human Keratinocytes upon Cytosolic RNA- and DNA-Fragment Induction

Keratinocytes are non-professional immune cells contributing actively to innate immune responses partially by reacting to a wide range of molecular patterns by activating pattern recognition receptors. Cytosolic nucleotide fragments as pathogen- or self-derived trigger factors are activating inflammasomes and inducing anti-viral signal transduction pathways as well as inducing expression of inflammatory cytokines. We aimed to compare the induced inflammatory reactions in three keratinocyte cell types—normal human epidermal keratinocytes, the HaCaT cell line and the HPV-KER cell line—upon exposure to the synthetic RNA and DNA analogues poly(I:C) and poly(dA:dT) to reveal the underlying signaling events. Both agents induced the expression of interleukin-6 and tumor necrosis factor α in all cell types; however, notable kinetic and expression level differences were found. Western blot analysis revealed rapid activation of the nuclear factor κB (NF-κB), mitogen activated protein kinase and signal transducers of activator of transcription (STAT) signal transduction pathways in keratinocytes upon poly(I:C) treatment, while poly(dA:dT) induced slower activation. Inhibition of NF-κB, p38, STAT-1 and STAT-3 signaling resulted in decreased cytokine expression, whereas inhibition of mitogen-activated protein kinase kinase 1/2 (MEK1/2) signaling showed a negative feedback role in both poly(I:C)- and poly(dA:dT)-induced cytokine expression. Based on our in vitro results nucleotide fragments are able to induce inflammatory reactions in keratinocytes, but with different rate and kinetics of cytokine expression, explained by faster activation of signaling routes by poly(I:C) than poly(dA:dT).

Endothelial immune activation programmes cell-fate decisions and angiogenesis by inducing angiogenesis regulator DLL4 through TLR4-ERK-FOXC2 signalling

KEY POINTS

The mechanisms by which bacteria alter endothelial cell phenotypes and programme inflammatory angiogenesis remain unclear. In lung endothelial cells, we demonstrate that toll-like receptor 4 (TLR4) signalling induces activation of forkhead box protein C2 (FOXC2), a transcriptional factor implicated in lymphangiogenesis and endothelial specification, in an extracellular signal-regulated kinase (ERK)-dependent manner. TLR4-ERK-FOXC2 signalling regulates expression of the Notch ligand DLL4 and signals inflammatory angiogenesis in vivo and in vitro. Our work reveals a novel link between endothelial immune signalling (TLR pathway) and a vascular transcription factor, FOXC2, that regulates embryonic vascular development. This mechanism is likely to be relevant to pathological angiogenesis complicating inflammatory diseases in humans.

ABSTRACT

Endothelial cells (ECs) mediate a specific and robust immune response to bacteria in sepsis through the activation of toll-like receptor (TLR) signalling. The mechanisms by which bacterial ligands released during sepsis programme EC specification and altered angiogenesis remain unclear. We postulated that the forkhead box protein C2 (FOXC2) transcriptional factor directs EC cell-fate decisions and angiogenesis during TLR signalling. In human lung ECs, lipopolysaccharide (LPS) induced ERK phosphorylation, FOXC2, and delta-like 4 (DLL4, the master regulator of sprouting angiogenesis expression) in a TLR4-dependent manner. LPS-mediated ERK phosphorylation resulted in FOXC2-ERK protein ligation, ERK-dependent FOXC2 serine and threonine phosphorylation, and subsequent activation of DLL4 gene expression. Chemical inhibition of ERK or ERK-2 dominant negative transfection disrupted LPS-mediated FOXC2 phosphorylation and transcriptional activation of FOXC2. FOXC2-siRNA or ERK-inhibition attenuated LPS-induced DLL4 expression and angiogenic sprouting in vitro. In vivo, intraperitoneal LPS induced ERK and FOXC2 phosphorylation, FOXC2 binding to DLL4 promoter, and FOXC2/DLL4 expression in the lung. ERK-inhibition suppressed LPS-induced FOXC2 phosphorylation, FOXC2-DLL4 promoter binding, and induction of FOXC2 and DLL4 in mouse lung ECs. LPS induced aberrant retinal angiogenesis and DLL4 expression in neonatal mice, which was attenuated with ERK inhibition. FOXC2^+/- mice treated with LPS showed a mitigated increase in FOXC2 and DLL4 compared to FOXC2^+/+ mice. These data reveal a new mechanism (TLR4-ERK-FOXC2-DLL4) by which sepsis-induced EC TLR signalling programmes EC specification and altered angiogenesis.

Vasoactive intestinal peptide inhibits airway smooth muscle cell proliferation in a mouse model of asthma via the ERK1/2 signaling pathway

Asthma is a heterogeneous clinical syndrome characterized by airway inflammation, hyper-responsiveness and remodeling. Airway remodeling is irreversible by current antiasthmatic drugs, and it is the main cause of severe asthma. Airway smooth muscle cells (ASMCs) act as the main effector cells for airway remodeling; the proliferation and hypertrophy of which are involved in airway remodeling. Caveolin (Cav)- 1 is present on the surface of ASMCs, which is involved in cell cycle and signal transduction regulation, allowing ASMCs to change from proliferation to apoptosis. The extracellular signal-regulated kinase (ERK)1/2 signaling pathway is a common pathway regulated by various proliferative factors, which demonstrates a regulatory role in airway remodeling of asthma. There have been many studies on the correlation between vasoactive intestinal peptide (VIP) and airway reactivity and inflammation in asthma, but the functions and related mechanisms of ASMCs remain unclear. In this study, we established an airway remodeling model in asthmatic mice, and concluded that VIP inhibits airway remodeling in vivo. The in vitro effect of VIP on interleukin-13-induced proliferation of ASMCs was studied by examining the effects of VIP on expression of ERK1/2, phospho-ERK1/2 and Cav-1 in ASMCs, as well as changes in cell cycle distribution. VIP inhibited phosphorylation of the ERK1/2 signaling pathway and expression of Cav-1 on ASMCs and decreased the proportion of S phase cells in the cell cycle, thus inhibiting the proliferation of ASMCs. This study provides a novel therapeutic mechanism for the treatment of asthma.

Salvianolic acid B improves airway hyperresponsiveness by inhibiting MUC5AC overproduction associated with Erk1/2/P38 signaling

Salvianolic acid B (SalB) is one of the main water-soluble composites from Chinese medicine Dansen (Radix miltiorrhiza). It is used for clinical treatment of various diseases including cardiovascular, lung, Liver, renal and cancers. However, the effects of SalB to allergy induced airway mucin hypersecretion, inflammation and hyperresponsiveness (AHR) remains not clear. Overproduction of airway MUC5AC is a central effector of inflammation that is strongly associated with AHR in asthmatic attack. In this study, we investigated the anti-asthmatic activity and mechanism of SalB in a murine model and human epithelial cells by monitoring changes in mucin expression and secretion, airway inflammation, AHR, and signaling pathways. SalB was administered by intragastric administration (i.g) daily for a week, starting at 21 days after sensitization of ovalbumin (OVA). All examinations were performed 24h after the last antigen challenge. We found that treatments with SalB significantly inhibited increase in the tracheobronchial secretion, glycosaminoglycan levels, interleukin (IL)-13, IL-4, and IL-5 cytokines mRNA and protein expression, and decrease in mucociliary clearance in lung tissues. Histological results demonstrated that SalB attenuated OVA-induced eosinophil infiltration, airway goblet cell hyperplasia, and MUC5AC and MUC5B mRNA and protein expression in lung tissues. SalB exhibited protective effects against AHR in OVA-challenged animals. In vitro, SalB significantly inhibited IL-13-induced MUC5AC and MUC5B mRNA and protein expression in human epithelial cells. These effects were blocked by SalB by downregulating the Erk1/2 and P38 signaling pathways. Taken together, these data indicate that treatment with SalB may improve AHR by inhibiting MUC5AC overproduction.

Cyclic AMP Pathway Suppress Autoimmune Neuroinflammation by Inhibiting Functions of Encephalitogenic CD4 T Cells and Enhancing M2 Macrophage Polarization at the Site of Inflammation

Although it has been demonstrated that cAMP pathway affect both adaptive and innate cell functions, the role of this pathway in the regulation of T-cell-mediated central nervous system (CNS) autoimmune inflammation, such as in experimental autoimmune encephalomyelitis (EAE), remains unclear. It is also unclear how cAMP pathway affects the function of CD4 T cells in vivo at the site of inflammation. We found that adenylyl cyclase activator Forskolin besides inhibition of functions autoimmune CD4 T cells also upregulated microRNA (miR)-124 in the CNS during EAE, which is associated with M2 phenotype of microglia/macrophages. Our study further established that in addition to direct influence of cAMP pathway on CD4 T cells, stimulation of this pathway promoted macrophage polarization toward M2 leading to indirect inhibition of function of T cells in the CNS. We demonstrated that Forskolin together with IL-4 or with Forskolin together with IL-4 and IFNγ effectively stimulated M2 phenotype of macrophages indicating high potency of this pathway in reprogramming of macrophage polarization in Th2- and even in Th1/Th2-mixed inflammatory conditions such as EAE. Mechanistically, Forskolin and/or IL-4 activated ERK pathway in macrophages resulting in the upregulation of M2-associated molecules miR-124, arginase (Arg)1, and Mannose receptor C-type 1 (Mrc1), which was reversed by ERK inhibitors. Administration of Forskolin after the onset of EAE substantially upregulated M2 markers Arg1, Mrc1, Fizz1, and Ym1 and inhibited M1 markers nitric oxide synthetase 2 and CD86 in the CNS during EAE resulting in decrease in macrophage/microglia activation, lymphocyte and CD4 T cell infiltration, and the recovery from the disease. Forskolin inhibited proliferation and IFNγ production by CD4 T cells in the CNS but had rather weak direct effect on proliferation of autoimmune T cells in the periphery and in vitro, suggesting prevalence of indirect effect of Forskolin on differentiation and functions of autoimmune CD4 T cells in vivo. Thus, our data indicate that Forskolin has potency to skew balance toward M2 affecting ERK pathway in macrophages and indirectly inhibit pathogenic CD4 T cells in the CNS leading to the suppression of autoimmune inflammation. These data may have also implications for future therapeutic approaches to inhibit autoimmune Th1 cells at the site of tissue inflammation.

Inhibition of soluble epoxide hydrolase attenuates eosinophil recruitment and food allergen-induced gastrointestinal inflammation

Prevalence of food allergies in the United States is on the rise. Eosinophils are recruited to the intestinal mucosa in substantial numbers in food allergen-driven gastrointestinal (GI) inflammation. Soluble epoxide hydrolase (sEH) is known to play a pro-inflammatory role during inflammation by metabolizing anti-inflammatory epoxyeicosatrienoic acids (EETs) to pro-inflammatory diols. We investigated the role of sEH in a murine model of food allergy and evaluated the potential therapeutic effect of a highly selective sEH inhibitor (trans-4-{4-[3-(4-trifluoromethoxyphenyl)-ureido]-cyclohexyloxy}-benzoic acid [t-TUCB]). Oral exposure of mice on a soy-free diet to soy protein isolate (SPI) induced expression of intestinal sEH, increased circulating total and antigen-specific IgE levels, and caused significant weight loss. Administration of t-TUCB to SPI-challenged mice inhibited IgE levels and prevented SPI-induced weight loss. Additionally, SPI-induced GI inflammation characterized by increased recruitment of eosinophils and mast cells, elevated eotaxin 1 levels, mucus hypersecretion, and decreased epithelial junction protein expression. In t-TUCB-treated mice, eosinophilia, mast cell recruitment, and mucus secretion were significantly lower than in untreated mice and SPI-induced loss of junction protein expression was prevented to variable levels. sEH expression in eosinophils was induced by inflammatory mediators TNF-α and eotaxin-1. Treatment of eosinophils with t-TUCB significantly inhibited eosinophil migration, an effect that was mirrored by treatment with 11,12-EET, by inhibiting intracellular signaling events such as ERK (1/2) activation and eotaxin-1-induced calcium flux. These studies suggest that sEH induced by soy proteins promotes allergic responses and GI inflammation including eosinophilia and that inhibition of sEH can attenuate these responses.

The role of Src & ERK1/2 kinases in inspiratory resistive breathing induced acute lung injury and inflammation

Background

Inspiratory resistive breathing (IRB), a hallmark of obstructive airway diseases, is associated with large negative intrathoracic pressures, due to strenuous contractions of the inspiratory muscles. IRB is shown to induce lung injury in previously healthy animals. Src is a multifunctional kinase that is activated in the lung by mechanical stress. ERK1/2 kinase is a downstream target of Src. We hypothesized that Src is activated in the lung during IRB, mediates ERK1/2 activation and IRB-induced lung injury.

Methods

Anaesthetized, tracheostomized adult rats breathed spontaneously through a 2-way non-rebreathing valve. Resistance was added to the inspiratory port to provide a peak tidal inspiratory pressure of 50% of maximum (inspiratory resistive breathing). Activation of Src and ERK1/2 in the lung was estimated during IRB. Following 6 h of IRB, respiratory system mechanics were measured by the forced oscillation technique and bronchoalveolar lavage (BAL) was performed to measure total and differential cell count and total protein levels. IL-1b and MIP-2a protein levels were measured in lung tissue samples. Wet lung weight to total body weight was measured and Evans blue dye extravasation was estimated to measure lung permeability. Lung injury was evaluated by histology. The Src inhibitor, PP-2 or the inhibitor of ERK1/2 activation, PD98059 was administrated 30 min prior to IRB.

Results

Src kinase was activated 30 min after the initiation of IRB. Src inhibition ameliorated the increase in BAL cellularity after 6 h IRB, but not the increase of IL-1β and MIP-2a in the lung. The increase in BAL total protein and lung injury score were not affected. The increase in tissue elasticity was partly inhibited. Src inhibition blocked ERK1/2 activation at 3 but not at 6 h of IRB. ERK1/2 inhibition ameliorated the increase in BAL cellularity after 6 h of IRB, blocked the increase of IL-1β and returned Evans blue extravasation and wet lung weight to control values. BAL total protein and the increase in elasticity were partially affected. ERK1/2 inhibition did not significantly change total lung injury score compared to 6 h IRB.

Conclusions

Src and ERK1/2 are activated in the lung following IRB and participate in IRB-induced lung injury.

β2-Adrenoceptor signaling in airway epithelial cells promotes eosinophilic inflammation, mucous metaplasia, and airway contractility

The mostly widely used bronchodilators in asthma therapy are β₂-adrenoreceptor (β₂AR) agonists, but their chronic use causes paradoxical adverse effects. We have previously determined that β₂AR activation is required for expression of the asthma phenotype in mice, but the cell types involved are unknown. We now demonstrate that β₂AR signaling in the airway epithelium is sufficient to mediate key features of the asthmatic responses to IL-13 in murine models. Our data show that inhibition of β₂AR signaling with an aerosolized antagonist attenuates airway hyperresponsiveness (AHR), eosinophilic inflammation, and mucus-production responses to IL-13, whereas treatment with an aerosolized agonist worsens these phenotypes, suggesting that β₂AR signaling on resident lung cells modulates the asthma phenotype. Labeling with a fluorescent β₂AR ligand shows the receptors are highly expressed in airway epithelium. In β₂AR^-/- mice, transgenic expression of β₂ARs only in airway epithelium is sufficient to rescue IL-13-induced AHR, inflammation, and mucus production, and transgenic overexpression in WT mice exacerbates these phenotypes. Knockout of β-arrestin-2 (βarr-2^-/-) attenuates the asthma phenotype as in β₂AR^-/- mice. In contrast to eosinophilic inflammation, neutrophilic inflammation was not promoted by β₂AR signaling. Together, these results suggest β₂ARs on airway epithelial cells promote the asthma phenotype and that the proinflammatory pathway downstream of the β₂AR involves βarr-2. These results identify β₂AR signaling in the airway epithelium as capable of controlling integrated responses to IL-13 and affecting the function of other cell types such as airway smooth muscle cells.

Fine particulate matter aggravates allergic airway inflammation through thymic stromal lymphopoietin activation in mice

Fine particulate matter (PM2.5) has been linked to exacerbation of allergic airway inflammation in mice. However, the mechanism underlying exposure to PM2.5 and subsequent and adverse effects remains to be fully elucidated. Therefore, the present study aimed to investigate the effects of PM2.5 by different levels on airway inflammation in mouse models of in allergic and steroid‑resistant asthma. BALB/c mice were nasally instilled with PBS (control) or 10, 31.6 or 100 µg PM2.5, and randomly assigned into nine groups. The acute asthma model was previously induced to investigate the change of inflammatory cells in bronchoalveolar lavage fluid (BALF). Histopathological changes of the lung were assessed, in addition to levels of interleukin (IL)‑4 and IL‑13 in BALF and immunoglobulin Ein serum. Thymic stromal lymphopoietin (TSLP) proteinexpression levels were assessed by western blotting. The present study demonstrated that medium‑ and high‑dose PM2.5 is linked to acute exacerbation of allergic airway inflammation in mice. In conclusion, the pathological mechanisms of PM2.5 may be associated with allergic/steroid‑resistant airway inflammation, T‑cell helper (Th)1/Th2 cytokine production and upregulation of TSLP expression in a murine model of allergic and steroid-resistant asthma.

Tangeretin has anti-asthmatic effects via regulating PI3K and Notch signaling and modulating Th1/Th2/Th17 cytokine balance in neonatal asthmatic mice

Asthma is a chronic allergic disease characterized by airway inflammation, airway hyper-responsiveness (AHR), and mucus hypersecretion. T-lymphocytes are involved in the pathogenesis of asthma, mediating airway inflammatory reactions by secreting cytokines. The phosphoinositide 3-kinase (PI3K) and Notch signaling pathways are associated with T cell signaling, proliferation, and differentiation, and are important in the progression of asthma. Thus, compounds that can modulate T cell proliferation and function may be of clinical value. Here, we assessed the effects of tangeretin, a plant-derived flavonoid, in experimental asthma. BALB/c mice at postnatal day (P) 12 were challenged with ovalbumin (OVA). Separate groups of mice (n=18/group) were administered tangeretin at 25 or 50 mg/kg body weight by oral gavage. Dexamethasone was used as a positive control. Tangeretin treatment reduced inflammatory cell infiltration in bronchoalveolar lavage fluid (BALF) and also restored the normal histology of lung tissues. OVA-specific IgE levels in serum and BALF were reduced. AHR, as determined by airway resistance and lung compliance, was normalized. Flow cytometry analyses revealed a reduced Th17 cell population. Tangeretin reduced the levels of Th2 and Th17 cytokines and raised IFN-γ levels. PI3K signaling was inhibited. The expressions of the Notch 1 receptor and its ligands Jagged 1 and 2 were downregulated by tangeretin. Our findings support the possible use of tangeretin for treating allergic asthma.

Effects of β-blockers on house dust mite-driven murine models pre- and post-development of an asthma phenotype

BACKGROUND

Our previous studies suggested certain β-adrenoceptor blockers (β-blockers) attenuate the asthma phenotype in ovalbumin driven murine models of asthma. However, the ovalbumin model has been criticized for lack of clinical relevance.

METHODS

We tested the non-selective β-blockers, carvedilol and nadolol, in house dust mite (HDM) driven murine asthma models where drugs were administered both pre- and post-development of the asthma phenotype. We measured inflammation, mucous metaplasia, and airway hyper-responsiveness (AHR). We also measured the effects of the β-blockers on extracellular-signal regulated kinase (ERK 1/2) phosphorylation in lung homogenates.

RESULTS

We show that nadolol, but not carvedilol, attenuated inflammation and mucous metaplasia, and had a moderate effect attenuating AHR. Following HDM exposure, ERK1/2 phosphorylation was elevated, but the level of phosphorylation was unaffected by β-blockers, suggesting ERK1/2 phosphorylation becomes dissociated from the asthma phenotype.

CONCLUSION

Our findings in HDM models administering drugs both pre- and post-development of the asthma phenotype are consistent with previous results using ovalbumin models and show differential effects for nadolol and carvedilol on the asthma phenotype. Lastly, our data suggest that ERK1/2 phosphorylation may be involved in development of the asthma phenotype, but may have a limited role in maintaining the phenotype.

Spectrum of T-lymphocyte activities regulating allergic lung inflammation

Despite advances in the treatment of asthma, optimization of symptom control remains an unmet need in many patients. These patients, labeled severe asthma, are responsible for a substantial fraction of the disease burden. In these patients, research is needed to define the cellular and molecular pathways contributing to disease which in large part are refractory to corticosteroid treatment. The causes of steroid-resistant asthma are multifactorial and result from complex interactions of genetics, environmental factors, and innate and adaptive immunity. Adaptive immunity, addressed here, integrates the activities of distinct T-cell subsets and by definition is dynamic and responsive to an ever-changing environment and the influences of epigenetic modifications. These T-cell subsets exhibit different susceptibilities to the actions of corticosteroids and, in some, corticosteroids enhance their functional activation. Moreover, these subsets are not fixed in lineage differentiation but can undergo transcriptional reprogramming in a bidirectional manner between protective and pathogenic effector states. Together, these factors contribute to asthma heterogeneity between patients but also in the same patient at different stages of their disease. Only by carefully defining mechanistic pathways, delineating their sensitivity to corticosteroids, and determining the balance between regulatory and effector pathways will precision medicine become a reality with selective and effective application of targeted therapies.

Phosphodiesterase 4 Inhibitors Attenuate the Asthma Phenotype Produced by β2-Adrenoceptor Agonists in Phenylethanolamine N-Methyltransferase-Knockout Mice

Mice lacking the endogenous β2-adrenoceptor (β2AR) agonist epinephrine (phenylethanolamine N-methyltransferase [PNMT]-knockout mice) are resistant to developing an "asthma-like" phenotype in an ovalbumin sensitization and challenge (Ova S/C) model, and chronic administration of β2AR agonists to PNMT-KO mice restores the phenotype. Based on these and other studies showing differential effects of various β2AR ligands on the asthma phenotype, we have speculated that the permissive effect of endogenous epinephrine and exogenous β2AR agonists on allergic lung inflammation can be explained by qualitative β2AR signaling. The β2AR can signal through at least two pathways: the canonical Gαs-cAMP pathway and a β-arrestin-dependent pathway. Previous studies suggest that β-arrestin-2 is required for allergic lung inflammation. On the other hand, cell-based assays suggest antiinflammatory effects of Gαs-cAMP signaling. This study was designed to test whether the in vitro antiinflammatory effects of phosphodiesterase 4 inhibitors, known to increase intracellular cAMP in multiple airway cell types, attenuate the asthma-like phenotype produced by the β2AR agonists formoterol and salmeterol in vivo in PNMT-KO mice, based on the hypothesis that skewing β2AR signaling toward Gαs-cAMP pathway is beneficial. Airway inflammatory cells, epithelial mucus production, and airway hyperresponsiveness were quantified. In Ova S/C PNMT-KO mice, formoterol and salmeterol restored the asthma-like phenotype comparable to Ova S/C wild-type mice. However, coadministration of either roflumilast or rolipram attenuated this formoterol- or salmeterol-driven phenotype in Ova S/C PNMT-KO. These findings suggest that amplification of β2AR-mediated cAMP by phosphodiesterase 4 inhibitors attenuates the asthma-like phenotype promoted by β-agonists.

Cystic fibrosis transmembrane conductance regulator mediates tenogenic differentiation of tendon-derived stem cells and tendon repair: accelerating tendon injury healing by intervening in its downstream signaling

Tendons are a mechanosensitive tissue, which enables them to transmit to bone forces that are derived from muscle. Patients with tendon injuries, such as tendinopathy or tendon rupture, were often observed with matrix degeneration, and the healing of tendon injuries remains a challenge as a result of the limited understanding of tendon biology. Our study demonstrates that the stretch-mediated activation channel, cystic fibrosis transmembrane conductance regulator (CFTR), was up-regulated in tendon-derived stem cells (TDSCs) during tenogenic differentiation under mechanical stretching. Tendon tissues in CFTR-dysfunctional DF508 mice exhibited irregular cell arrangement, uneven fibril diameter distribution, weak mechanical properties, and less matrix formation in a tendon defect model. Moreover, both tendon tissues and TDSCs isolated from DF508 mice showed significantly decreased levels of tendon markers, such as scleraxis, tenomodulin, Col1A1 (collagen type I α 1 chain), and decorin Furthermore, by RNA sequencing analysis, we demonstrated that Wnt/β-catenin signaling was abnormally activated in TDSCs from DF508 mice, thereby further activating the pERK1/2 signaling pathway. Of most importance, we found that intervention in pERK1/2 signaling could promote tenogenic differentiation and tendon regeneration both in vitro and in vivo Taken together, our study demonstrates that CFTR plays an important role in tenogenic differentiation and tendon regeneration by inhibiting the β-catinin/pERK1/2 signaling pathway. The therapeutic strategy of intervening in the CFTR/β-catenin/pERK1/2 regulatory axis may be helpful for accelerating tendon injury healing, which has implications for tendon injury management.-Liu, Y., Xu, J., Xu, L., Wu, T., Sun, Y., Lee, Y.-W., Wang, B., Chan, H.-C., Jiang, X., Zhang, J., Li, G. Cystic fibrosis transmembrane conductance regulator mediates tenogenic differentiation of tendon-derived stem cells and tendon repair: accelerating tendon injury healing by intervening in its downstream signaling.

The FOXM1 inhibitor RCM-1 suppresses goblet cell metaplasia and prevents IL-13 and STAT6 signaling in allergen-exposed mice

Goblet cell metaplasia and excessive mucus secretion associated with asthma, cystic fibrosis, and chronic obstructive pulmonary disease contribute to morbidity and mortality worldwide. We performed a high-throughput screen to identify small molecules targeting a transcriptional network critical for the differentiation of goblet cells in response to allergens. We identified RCM-1, a nontoxic small molecule that inhibited goblet cell metaplasia and excessive mucus production in mice after exposure to allergens. RCM-1 blocked the nuclear localization and increased the proteasomal degradation of Forkhead box M1 (FOXM1), a transcription factor critical for the differentiation of goblet cells from airway progenitor cells. RCM-1 reduced airway resistance, increased lung compliance, and decreased proinflammatory cytokine production in mice exposed to the house dust mite and interleukin-13 (IL-13), which triggers goblet cell metaplasia. In cultured airway epithelial cells and in mice, RCM-1 reduced IL-13 and STAT6 (signal transducer and activator of transcription 6) signaling and prevented the expression of the STAT6 target genes Spdef and Foxa3, which are key transcriptional regulators of goblet cell differentiation. These results suggest that RCM-1 is an inhibitor of goblet cell metaplasia and IL-13 signaling, providing a new therapeutic candidate to treat patients with asthma and other chronic airway diseases.

Anti‑inflammatory effects of dihydromyricetin in a mouse model of asthma

Dihydromyricetin (DHM) is a plant flavonoid and is the primary active ingredient isolated from the medicinal herb, Ampelopsis grossedentata. DHM has been shown to possess various pharmacological activities, including anti-inflammatory effects. However, the possible role of DHM in asthma treatment remains to be elucidated. The present study aimed to investigate its anti-inflammatory properties in mice with symptoms of allergic asthma. The C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) to induce asthma. DHM or phosphate-buffered saline treatment was administered 1 h prior to the OVA challenge. The levels of interleukin (IL)-4, IL-5 and IL-13 in the bronchoalveolar lavage (BAL) fluid were measured by enzyme-linked immunosorbent assay (ELISA), and OVA-specific serum IgE and IgG1 levels were also determined by ELISA. Histopathological staining was performed to evaluate the infiltration of inflammatory cells into the BAL fluid, lung tissues and goblet cell hyperplasia. DHM treatment significantly reduced the total number of inflammatory cells, including eosinophils, neutrophils, lymphocytes and macrophages, in the BAL fluid. DHM also reduced the levels of IL-4, IL-5 and IL-13 in the BAL fluid, and reduced the secretion of OVA-specific IgE and IgG1 in the serum. The histological staining demonstrated that DHM treatment effectively suppressed the OVA-induced inflammatory cells in the lung tissues and in the mucus hypersecreted by goblet cells in the airway. These results showed that DHM had a potent anti-inflammatory effect in an OVA-induced mouse model of asthma, offering potential as an anti-inflammatory agent for the treatment of asthma.

Mandevilla longiflora (Desf.) Pichon improves airway inflammation in a murine model of allergic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Mandevilla longiflora, popularly known as "velame" in central Brazil, is a subshrub widely distributed in South America. Its xylopodium is used in the form of a decoction or infusion to treat inflammation and other ailments.

AIM OF THE STUDY

This study aimed to evaluate the anti-inflammatory potential of M. longiflora in an in vivo model of ovalbumin-induced immediate hypersensitivity, identifying its effects on leukocyte infiltration, IgE and LTB₄ levels, and Th2 cytokine production. In addition, HPLC fingerprint of the extract was performed.

MATERIAL AND METHODS

The hydroethanolic extract 70% of M. longiflora (HEMI) was obtained by maceration of the plant xylopodium. Swiss mice were sensitized by i.p. injection OVA-aluminium hydroxide on days 1 and 10. Nine days after the last sensitisation animals were challenged for 6 consecutive days with OVA solution for 20min daily in a closed chamber under continuous flow of aerosol. The animals were treated with HEMl (20, 50 and 200mg/kg p.o.), 2 times per day, and euthanized 24h later. Animals treated with vehicle (2% Tween-20) or dexamethasone were used as negative and positive controls, respectively. The recruitment of inflammatory cells into the pulmonary cavity was evaluated by counting cells present in broncho-alveolar lavage fluid (BALF). Lung tissue was also collected for histopathology and infiltration analysis. Quantification of IL-4, IL-5 and IL-13 from the BALF, and IgE, and LTB₄ from plasma, were conducted by immunoassay.

RESULTS AND CONCLUSIONS

The HEMl attenuated leukocyte migration into the airways, which was evidenced by a decrease in eosinophils, neutrophils and mononuclear cells, both in BALF quantification and by histopathological analysis, as well as decreasing the concentrations of IL-4, IL-5, IL-13, IgE and LTB₄. All of these events are typical of air-mucosa inflammatory disease. These findings scientifically evidence for the first time the ethnopharmacological use of M. longiflora to treat chronic inflammatory events, such as asthma, and suggest a potential therapeutic use or complementary therapy for this plant extract.

β2-receptor agonists salbutamol and terbutaline attenuated cytokine production by suppressing ERK pathway through cAMP in macrophages

β₂-receptor agonists are used in the treatment of inflammatory obstructive lung diseases asthma and COPD as a symptomatic remedy, but they have been suggested to possess anti-inflammatory properties, also. β₂-receptor activation is considered to lead to the activation of ERK pathway through G-protein- and cAMP-independent mechanisms. In this study, we investigated the effects of β₂-receptor agonists salbutamol and terbutaline on the production of inflammatory factors in macrophages. We found that β₂-receptor agonists inhibited LPS-induced ERK phosphorylation and the production of MCP-1. A chemical cAMP analog 8-Br-cAMP also inhibited ERK phosphorylation and TNF and MCP-1 release. As expected, MAPK/ERK kinase (MEK)1/2 inhibitor PD0325901 inhibited ERK phosphorylation and suppressed both TNF and MCP-1 production. In conclusion, we suggest that β₂-receptor agonists salbutamol and terbutaline inhibit inflammatory gene expression partly by a mechanism dependent on cAMP leading to the inhibition of ERK signaling in macrophages. Observed anti-inflammatory effects of β₂-receptor agonists may contribute to the clinical effects of these drugs.

Anti-asthmatic activity of osthole in an ovalbumin-induced asthma murine model

Osthole, an active coumarin extracted from the dried fruits of Cnidium monnieri (L.) Cusson, is known to possess a variety of pharmacological activities. In the present study, we investigated and illuminated the mechanisms underlying the protective effects of osthole in an experimental model of allergic asthma. Our results show that osthole treatment significantly reduced the OVA-induced increase in serum IgE and inflammatory cytokines (IL-4, IL-5, IL-13) in bronchoalveolar lavage fluid (BALF), and decreased the recruitment of inflammatory cells in BALF and the lung. It also effectively attenuated goblet cell hyperplasia and mucus overproduction in lung tissue. In addition, western blot analysis demonstrated that osthole blocked NF-κB activation, which may be associated with a reduction in inflammatory cytokine production. These data suggest that osthole attenuated OVA-induced allergic asthma inflammation by inhibiting NF-κB activation. The present study identified the molecular mechanisms of action of osthole, which support the potential pharmaceutical application of osthole treatment for asthma and other airway inflammation disorders.

Naringin Protects Ovalbumin-Induced Airway Inflammation in a Mouse Model of Asthma

Many plant species containing flavonoids have been widely used in traditional Chinese medicine. Naringin, a well-known flavanone glycoside of citrus fruits, possesses antioxidant, anti-inflammatory, anti-apoptotic, anti-ulcer, anti-osteoporosis, and anti-carcinogenic properties. The aim of the study was to investigate the anti-asthmatic effects of naringin and the possible mechanisms. Asthma model was established by ovalbumin. A total of 50 mice were randomly assigned to five experimental groups: control, model, and dexamethasone (2 mg/kg, orally) and naringin (5 mg/kg, 10 mg/kg, orally). Airway resistance (Raw) were measured, histological studies were evaluated by the hematoxylin and eosin (HE) staining, OVA-specific serum and BALF IgE levels and Th1/Th2 cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA), and Th1/Th2 cells was evaluated by flow cytometry (FCM). T-bet and GABA3 in the lung were evaluated by Western blot. Our study demonstrated that naringin inhibited OVA-induced increases in Raw and eosinophil count; OVA-induced effects on interleukin (IL)-4 and INF-gamma levels were blunted with naringin administration. Histological studies demonstrated that naringin substantially inhibited OVA-induced eosinophilia in lung tissue and airway tissue. Flow cytometry studies demonstrated that naringin substantially inhibited Th2 cells and enhanced Th1 cells. Naringin substantially inhibited GABA3 and increased T-bet. These findings suggest that naringin may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

Oroxylin A Inhibits Allergic Airway Inflammation in Ovalbumin (OVA)-Induced Asthma Murine Model

Oroxylin A, a natural flavonoid isolated from the medicinal herb Scutellaria baicalensis Georgi, has been reported to have anti-inflammatory property. In this study, we aimed to investigate the protective effects and mechanism of oroxylin A on allergic inflammation in OVA-induced asthma murine model. BABL/c mice were sensitized and airway-challenged with OVA to induce asthma. Oroxylin A (15, 30, and 60 mg/kg) was administered by oral gavage 1 h before the OVA treatment on day 21 to 23. The results showed that oroxylin A attenuated OVA-induced lung histopathologic changes, airway hyperresponsiveness, and the number of inflammatory cells. Oroxylin A also inhibited the levels of IL-4, IL-5, IL-13, and OVA-specific IgE in BALF. Furthermore, oroxylin A significantly inhibited OVA-induced NF-κB activation. In conclusion, these results suggested that oroxylin A inhibited airway inflammation in OVA-induced asthma murine model by inhibiting NF-κB activation. These results suggested that oroxylin A was a potential therapeutic drug for treating allergic asthma.

Therapeutic effects of rosmarinic acid on airway responses in a murine model of asthma

Rosmarinic acid (RA) is an active component of a traditional Chinese herbal medicine. Previously, we reported that RA exerted a strong anti-inflammatory effect in a mouse acute lung injury model. Therefore, we hypothesized that RA might also have potential therapeutic effects in a murine model of asthma. In this study, we aimed to evaluate the anti-asthmatic activity of RA and explored its possible molecular mechanisms of action. Female BALB/c mice that had been sensitized to and challenged with ovalbumin (Ova) were treated with RA (20mg/kg) 1h after challenge. The results showed that RA greatly diminished the number of inflammatory cells and the production of Th2 cytokines in the bronchoalveolar lavage fluid (BALF); significantly reduced the secretion of total IgE, Ova-specific IgE, and eotaxin; and markedly ameliorated airway hyperresponsiveness (AHR) compared with Ova-induced mice. Histological studies further revealed that RA substantially decreased inflammatory cells infiltration and mucus hypersecretion compared with Ova-induced mice. Moreover, our results suggested that the protective effects of RA were mediated by the inhibition of JNK and p38 MAPK phosphorylation and nuclear factor-κB (NF-κB) activation. Furthermore, RA treatment resulted in a significant reduction in the mRNA expression of AMCase, CCL11, CCR3, Ym2 and E-selectin in lung tissue. These findings suggest that RA may effectively delay the development of airway inflammation and could thus be used as a therapy for allergic asthma.

EP4 Receptor-Associated Protein in Macrophages Protects against Bleomycin-Induced Pulmonary Inflammation in Mice

Excessive activation of inflammatory macrophages drives the pathogenesis of many chronic diseases. EP4 receptor-associated protein (EPRAP) has been identified as a novel, anti-inflammatory molecule in macrophages. In this study, we investigated the role of EPRAP using a murine model of bleomycin (BLM)-induced pulmonary inflammation. When compared with wild-type mice, EPRAP-deficient mice exhibited significantly higher mortality, and increased accumulation of macrophages and proinflammatory molecules in the lung 7 d post-BLM administration. Accordingly, the levels of phosphorylated p105, MEK1/2, and ERK1/2 were elevated in EPRAP-deficient alveolar macrophages following BLM administration. In contrast, macrophage-specific EPRAP overexpression decreased the production of proinflammatory cytokines and chemokines, suggesting that EPRAP in macrophages plays a key role in attenuating BLM-induced pulmonary inflammation. As EPRAP is phosphorylated after translation, we examined the role of posttranslational modifications in cellular inflammatory activation using mouse embryo fibroblasts (MEFs) expressing mutant EPRAP proteins. Expression of mutant EPRAP, in which serine-108 and serine-608 were replaced with alanine (EPRAP S108A/S608A), markedly suppressed TNF-α production in LPS-treated MEFs. Conversely, the serine phosphatase 2A (PP2A) inhibitor, cantharidic acid, increased LPS-induced TNF-α production in MEFs expressing wild-type EPRAP, but not in MEFs expressing EPRAP S108A/S608A. Immunoprecipitation analyses demonstrated that EPRAP associated with PP2A in both MEFs and alveolar macrophages from BLM-treated mice. Our data suggest that PP2A dephosphorylates EPRAP, which may be a crucial step in exertion of its anti-inflammatory properties. For these reasons, we believe the EPRAP-PP2A axis in macrophages holds the key to treating chronic inflammatory disorders.

Investigation of the anti‑asthmatic activity of Oridonin on a mouse model of asthma

Oridonin is an extract obtained from a traditional Chinese medicinal herb, Xihuangcao. Previous studies have demonstrated that Oridonin exerts various pharmaceutical effects, such as anti-tumor and immunosuppressive effects, as well as modulating cytokine balance. The present study identified that Oridonin could regulate the T_h1/T_h2 cytokine balance in mice. However, as the anti-asthmatic effect of Oridonin is currently unknown a mouse model of asthma was used in the present study. BALB/c mice were sensitized using ovalbumin (OVA), then the sensitized mice were treated with Oridonin prior to OVA challenge. The in vivo study indicated that Oridonin decreased the OVA-induced airway hyper-responsiveness significantly (P<0.05). In addition, the results indicated that in Oridonin-treated mice, the eosinophil number and total inflammatory cell number in bronchoalveolar lavage (BAL) fluid decreased significantly in the Oridonin group when compared with the control group. Further study indicated that Oridonin significantly decreased the level of inflammatory cytokines, which were induced by OVA, in BAL fluid. Histological studies were performed to evaluate the effect of Oridonin on eosinophilia and mucus in the airway, the results indicated that Oridonin significantly inhibited the eosinophilia and mucus production in the lungs. Therefore the present study demonstrated that Oridonin regulates T_h1/T_h2 balance in mice and exhibited anti-asthmatic effects in a mouse model of asthma. These findings indicate that Oridonin may serve as a potential therapeutic compound for the treatment of asthma in future.

The MEK inhibitor trametinib separates murine graft-versus-host disease from graft-versus-tumor effects

The efficacy of allogeneic hematopoietic stem cell transplantation for hematologic malignancies is limited by the difficulty in suppressing graft-versus-host disease (GVHD) without compromising graft-versus-tumor (GVT) effects. We previously showed that RAS/MEK/ERK signaling depends on memory differentiation in human T cells, which confers susceptibility to selective inhibition of naive T cells. Actually, antineoplastic MEK inhibitors selectively suppress alloreactive T cells, sparing virus-specific T cells in vitro. Here, we show that trametinib, a MEK inhibitor clinically approved for melanoma, suppresses GVHD safely without affecting GVT effects in vivo. Trametinib prolonged survival of GVHD mice and attenuated GVHD symptoms and pathology in the gut and skin. It inhibited ERK1/2 phosphorylation and expansion of donor T cells, sparing Tregs and B cells. Although high-dose trametinib inhibited myeloid cell engraftment, low-dose trametinib suppressed GVHD without severe adverse events. Notably, trametinib facilitated the survival of mice transplanted with allogeneic T cells and P815 tumor cells with no residual P815 cells observed in the livers and spleens, whereas tacrolimus resulted in P815 expansion. These results confirm that trametinib selectively suppresses GVHD-inducing T cells while sparing antitumor T cells in vivo, which makes it a promising candidate for translational studies aimed at preventing or treating GVHD.

Astragalin Attenuates Allergic Inflammation in a Murine Asthma Model

The present study aimed to determine the protective effects and the underlying mechanisms of astragalin (AG) on ovalbumin (OVA)-induced allergic inflammation in a mouse model of allergic asthma. Our study demonstrated that AG inhibited OVA-induced increases in eosinophil count; IL-4, IL-5, IL-13, and IgE were recovered in bronchoalveolar lavage fluid, and increased IFN-γ level in bronchoalveolar lavage fluid. Histological studies demonstrated that AG substantially inhibited OVA-induced eosinophilia in lung tissue. Western blot analysis demonstrated that AG treatments markedly inhibited OVA-induced SOCS-3 expression and enhancement of SOCS-5 expression in an asthma model. Our findings support the possible use of AG as a therapeutic drug for patients with allergic asthma.

Anti-Asthmatic Effects of Ginsenoside Rb1 in a Mouse Model of Allergic Asthma Through Relegating Th1/Th2

The aim of the study was to investigate the anti-asthma effects of ginsenoside Rb1 (Rb1) and its possible mechanisms. A total of 50 mice were randomly assigned to five experimental groups: control, model, dexamethasone (2 mg/kg), and Rb1 (10 and 20 mg/kg). Airway resistance (RI) was measured; histological studies were evaluated by the hematoxylin and eosin (HE) staining; Th1/Th2, ovalbumin (OVA)-specific serum, and bronchoalveolar lavage fluid (BALF) IgE levels were evaluated enzyme-linked immunosorbent assay (ELISA); and T-bet/GATA3 proteins were evaluated by Western blot. Our study demonstrated that Rb1 inhibited OVA-induced increases in RI and eosinophil counts; interleukin (IL)-4 was recovered, and IFN-γlevel increased in bronchoalveolar lavage fluid. Histological studies demonstrated that Rb1 substantially inhibited OVA-induced eosinophilia in lung tissue. Western blot studies demonstrated that Rb1 substantially inhibited GATA3 and increased T-bet. These findings suggest that Rb1 may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

Role of selective blocking of bradykinin receptor subtypes in attenuating allergic airway inflammation in guinea pigs

The present study was designed to evaluate the potential role of bradykinin antagonists (R-715; bradykinin B1 receptor antagonist and icatibant; bradykinin B2 receptor antagonist) in treatment of allergic airway inflammation in comparison to dexamethasone and montelukast. R-715 as dexamethasone significantly decreased peribronchial leukocyte infiltration, bronchoalveolar lavage fluid (BALF) albumin and interleukin 1β as well as serum OVA-specific IgE level. Also, R-715 like montelukast significantly decreased BALF cell count (total and eosinophils). Icatibant showed negative results. The current findings suggest that selective bradykinin B1 receptor antagonists may have the therapeutic potential for the treatment of allergic airway inflammation.

Allosteric modulators of MEK1: drug design and discovery

Mitogen-activated protein kinase kinase (MAPKK, MEK) mediates signal transduction, controlling cell proliferation and survival. MEK occupies a key downstream position in the Ras-Raf-MEK-ERK signaling pathway, implying that inhibition of MEK will potently suppress tumor cell growth, with potential applications in cancer therapy. Based on the promising therapeutic effects of MEK modulators, continued efforts have been made in this class. Here, we review the discovery and development of MEK1 allosteric modulators, classifying them into four structural groups. The allosteric mechanisms and recent clinical progress involving these modulators are also reviewed.

An association between neuropeptide Y levels and leukocyte subsets in stress-exacerbated asthmatic mice

Neuropeptide Y (NPY) was recently proposed to be associated with stress and airway inflammation; however, this has rarely been studied in animal models of asthma. Twenty-four C57BL/6 mice were randomly divided into 3 groups of 8 each: naive control group, asthma group (with an established asthma model), and stressed asthma group (with established asthma and stress models). Bronchoalveolar lavage (BAL) fluid was collected for total cell counts using a hemocytometer and for cytological examinations by Wright stain. Differential inflammatory cell counts were performed to identify eosinophils, macrophages, neutrophils, and lymphocytes. NPY and corticosterone serum levels were determined with enzyme immunoassay kits. Stress was associated with increased airway inflammatory response, which was manifested by the accumulation of total leukocytes and eosinophils in the BAL fluid in comparison with the asthma and the control groups. The levels of NPY (p<0.05) and corticosterone (p<0.01) were elevated in the stressed asthma group in comparison with the control and asthma groups. The concentration of NPY and corticosterone positively correlated with the total leukocyte count (r=0.892, p<0.05 and r=0.937, p<0.01 respectively) and eosinophil numbers (r=0.806, p=0.053 and r=0.885, p<0.01 respectively). Stress may be associated with elevated peripheral NPY level, which was observed to be associated with exacerbated airway inflammation in asthmatic mice.

Antiasthmatic Effects of Eugenol in a Mouse Model of Allergic Asthma by Regulation of Vitamin D3 Upregulated Protein 1/NF-κB Pathway

The aim of the study was to investigate the antiasthmatic effects of eugenol (EUG) and the possible mechanisms. Asthma model was established by ovalbumin induction. A total of 50 mice were randomly assigned to five experimental groups: control, OVA, OVA + dexamethasone (2 mg/kg), OVA + EUG (10 mg/kg), and OVA + EUG (20 mg/kg). Airway resistance (Raw) were measured, histological studies were evaluated by the hematoxylin and eosin (HE) staining, interleukin-4 (IL-4) and interleukin-5 (IL-5) were evaluated by enzyme-linked immunosorbent assay (ELISA), Vitamin D3 upregulated protein 1 (VDUP1), IκBα, P-IκBα, NF-κBP65, and p-NF-κBP65 were measured by Western blotting. Our study demonstrated that EUG inhibited OVA-induced increases in Raw and eosinophil count; IL-4 and IL-5 were recovered. Histological studies demonstrated that EUG substantially inhibited OVA-induced eosinophilia in the lung tissue. Western blotting studies demonstrated that EUG substantially inhibited P-IκBα, NF-κBP65, and p-NF-κBP65 protein levels and increased VDUP1 and IκBα protein levels. These findings suggest that EUG may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

Uvaol attenuates pleuritis and eosinophilic inflammation in ovalbumin-induced allergy in mice

Uvaol, a triterpene present in olives and virgin olive oil, has been shown to possess anti-inflammatory properties and antioxidant effects. However, until now, no studies have demonstrated its potential effects on allergic inflammation. The aim of this study was to evaluate the anti-inflammatory effects of uvaol in a mouse model of allergy characterized by eosinophil-dominant inflammation in actively sensitized mice. The anti-inflammatory effect of uvaol was analyzed in two murine models of allergic inflammation (pleurisy and asthma). In these models, Swiss mice were sensitized and challenged with ovalbumin (OVA). In the pleurisy model, the pleural eosinophilic inflammation and IL-5 concentrations were examined 24h after the OVA challenge, while in the asthma model were examined the airway inflammation via bronchoalveolar lavage (BAL) fluid cytology and lung histopathology analyses. Our results showed that uvaol decreased the accumulation of eosinophils and the concentration of IL-5 in pleural effluent. Uvaol also demonstrated important anti-inflammatory activity by inhibiting production of IL-5 and influx of leukocytes, mainly of eosinophils, in BAL fluid, but without interfering with levels of reactive oxygen species in leukocytes. Moreover, the eosinophil infiltration, mucus production, number of alveoli that collapsed, and IL-5 levels in the lung were clearly decreased by uvaol treatment. These findings indicate that uvaol can be a good candidate for the treatment of allergic inflammation by inhibiting eosinophil influx and IL-5 production in ovalbumin-induced allergy.

Inhibitory effect of Zanthoxylum bungeanum seed oil on ovalbumin‑induced lung inflammation in a murine model of asthma

The present study aimed to investigate the therapeutic efficacy of Zanthoxylum bungeanum seed oil (Z. seed oil) to alleviate airway inflammation in asthmatic mice. The asthmatic mice were treated with vehicle, ovalbumin (OVA), or OVA + Z. seed oil (2 g/kg) for between 24 h and 14 days. Following treatment, inflammatory cell infiltration and pulmonary tissue damage were assessed by hematoxylin and eosin staining, and immunohistochemistry. The expression levels of pro‑inflammatory cytokines, chemokines, adhesion molecules and mitogen activated protein kinase signaling proteins were measured by enzyme‑linked immunosorbent assays, reverse transcription quantitative‑polymerase chain reaction and western blot analysis. In asthmatic mice, administration of Z. seed oil attenuated lung tissue injury and airway remodeling, and inhibited the infiltration of leukocytes and eosinophils into the airway by reducing the expression levels of inflammatory cytokines and chemokines compared with OVA‑treated mice (P<0.05). Z. seed oil also reduced the levels of inflammatory chemokine and adhesion molecules via downregulation of extracellular signal‑regulated kinase and activation of c‑JUN N‑terminal kinase in the Z. seed‑treated mice compared with OVA‑treated mice (P<0.05). Thus, data from the present study indicates that Z. seed oil can suppress pulmonary inflammation and tissue injury during asthma, and suggests that it may be used to effectively treat allergen‑induced asthma.

Platycodin D Attenuates Airway Inflammation in a Mouse Model of Allergic Asthma by Regulation NF-κB Pathway

In this work, the anti-asthma potential of platycodin D (PLD) was studied by investigation of its effect to suppress airway inflammation, a murine model of asthma and the possible mechanisms. A total of 50 mice were randomly assigned to five experimental groups: control, ovalbumin (OVA), OVA+dexamethasone (2 mg/kg) and OVA+PLD (40, 80 mg/kg). Airway resistance (Raw) were measured; airway histological studies were evaluated by the hematoxylin and eosin (HE) staining; interleukin-4 (IL-4), interleukin-5(IL-5), and interleukin-13 in bronchoalveolar lavage fluid (BALF) were evaluated by enzyme-linked immunosorbent assay (ELISA); NF-κBp65, p-NF-κBp65, p-IKKα, IKKα, p-IKKβ, p-IкBα, and IкBα of airway were measured by Western blotting. Our study demonstrated that PLD inhibited OVA-induced increases in Raw and eosinophil count in airway; IL-4, IL-5, and IL-13 were recovered in BALF. Histological studies demonstrated that PLD substantially inhibited OVA-induced eosinophilia in airway tissue. Western blotting studies demonstrated that PLD substantially inhibited NF-κB pathway. These findings suggest that PLD may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

PI3K and ERK1/2 kinase inhibition potentiate protease inhibitor to attenuate allergen induced Th2 immune response in mouse

Proteases affect immune response by activating PI3K, ERK1/2 and p38 kinase. In present study, therapeutic effect of PI3K, ERK1/2 and p38 kinase inhibitor in combination with serine protease inhibitor was evaluated in cockroach extract (CE) induced airway inflammatory disease. Mice were sensitized on day 0, 7 and 14 and challenged on day 27, 28 and 29 with CE. Mice were given PI3K, ERK1/2 and the p38 kinase inhibitor (iPI3K, iERK1/2 and the ip38) alone or with serine protease inhibitor 4-(2-Aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF), 1h before challenge. On day 30 airway resistance of mice were determined and euthanized to collect blood, BAL fluid and lung for analysis. CE immunized mice showed PI3K, ERK1/2 and p38 kinase activation, increased airway resistance, cellular infiltration, Th2 cytokines IgE and IgG1. AEBSF given to mice reduced the CE induced allergic response. AEBSF given in combination of iPI3K/iERK1/2 reduced cellular infiltration in lungs. Furthermore, iPI3K/iERK1/2 with AEBSF significantly reduced the CE induced Th2 cytokines in comparison to monotherapy of kinase inhibitor and AEBSF (P<0.05). The combination of iPI3K/iERK1/2 with AEBSF enhanced IL-12 level that could further provide a mean of Th2 reduction. Best effect in reduction of allergic response in mice was observed on administration of AEBSF with iPI3K. Conclusively, the combination of PI3K kinase inhibitor with AEBSF reduced allergen induced airway response and has therapeutic potential for add-on therapy in allergic airway disease.