Inhaled dexamethasone differentially attenuates disease relapse and established allergic asthma in mice

Development and Clinical Application of Phosphorus-Containing Drugs

Phosphorus-containing drugs belong to an important class of therapeutic agents and are widely applied in daily clinical practices. Structurally, the phosphorus-containing drugs can be classified into phosphotriesters, phosphonates, phosphinates, phosphine oxides, phosphoric amides, bisphosphonates, phosphoric anhydrides, and others; functionally, they are often designed as prodrugs with improved selectivity and bioavailability, reduced side effects and toxicity, or biomolecule analogues with endogenous materials and antagonistic endoenzyme supplements. This review summarized the phosphorus-containing drugs currently on the market as well as a few promising molecules at clinical studies, with particular emphasis on their structural features, biological mechanism, and indications.

Ferulic acid supresses Th2 immune response and prevents remodeling in ovalbumin-induced pulmonary allergy associated with inhibition of epithelial-derived cytokines

Asthma is characterized by intermittent airway obstruction and chronic inflammation, orchestrated primarily by Th2 cytokines. There is a strong rationale for developing new asthma therapies, since current treatment protocols present side effects and may not be effective in cases of difficult-to-control asthma. The purpose of this study was to evaluate the effect of ferulic acid, a phenolic acid commonly present in plants, in the ovalbumin-induced pulmonary allergy murine model.

METHODS

BALB/c mice were sensitized and challenged with ovalbumin, and treatments were provided by gavage. Six groups of mice (n = 6) were studied, labeled as: control, pulmonary allergy, dexamethasone, and 3 receiving ferulic acid (at 25, 50, and 100 mg/kg). Lung tissue, bronchoalveolar lavage fluid and serum were collected for analysis.

RESULTS

Ferulic acid treatment inhibited an established allergic Th2-response by decreasing the key features of pulmonary allergy, including lung and airway inflammation, eosinophil infiltration, mucus production and serum levels of OVA-specific IgE. These results were associated with lower levels of CCL20, CCL11 and CCL5 chemokines and IL-4, IL-5, IL-13, TSLP, IL-25 and IL-33 cytokines in lung tissue homogenate.

CONCLUSIONS

In this study it was demonstrated for the first time that ferulic acid treatment is able to suppress one of the main features of the airway remodeling, indicated by reduction of mucus production, besides the Th2 pathogenic response on ovalbumin-induced pulmonary allergy. Taken together, results shows that the immunopathological mechanism underlying these effects is linked to a reduction of the epithelial-derived chemokines and cytokines, suggesting that ferulic acid may be useful as a potential therapeutic agent for asthma.

Ligustrazine corrects Th1/Th2 and Treg/Th17 imbalance in a mouse asthma model

Asthma is an inflammatory disease closely associated with activated T cells in the lung. Imbalances in Th1/Th2 and Treg/Th17 have been found in asthmatic patients. Ligustrazine from the Chinese herb chuanxiong has been used in China in combination with glucocorticoids to treat asthma. Previous studies have proved that ligustrazine can modulate the expression of transcription factors for Th1 (T-bet) and Th2 (Gata-3) in asthma. In the present study, ligustrazine alleviated allergic airway inflammation in a mouse asthmatic model by reducing the influx of eosinophils and neutrophils, which was mediated, at least in part, by the regulation of Th1/Th2 and Treg/Th17 via the re-balance of cytokine profiles and of ratios of transcription factors, T-bet/Gata-3 and Foxp3/RORγt, thus providing new insights into the mechanisms of action for asthma treatment with ligustrazine.

Tiotropium bromide inhibits relapsing allergic asthma in BALB/c mice

Recurrent relapses of allergic lung inflammation in asthmatics may lead to airway remodeling and lung damage. We tested the efficacy of tiotropium bromide, a selective long-acting, muscarinic receptor antagonist as an adjunct therapy in relapses of allergic asthma in mice. We compared the effectiveness of local intranasal administration of tiotropium and dexamethasone in acute and relapsing allergic asthma in BALB/c mice. Although tiotropium at low doses is a potent bronchodilator, we tested higher doses to determine effectiveness on inflammation and mucus hypersecretion. A 5-day course of twice daily intranasal tiotropium or dexamethasone (1 mg/kg (b.w.)) suppressed airway eosinophils by over 87% during disease initiation and 88% at relapse compared to vehicle alone. Both drugs were comparable in their capacity to suppress airway and parenchymal inflammation and mucus hypersecretion, though tiotropium was better than dexamethasone at reducing mucus secretion during disease relapse. Despite treatment with either drug, serum antigen-specific IgE or IgG1 antibody titres remained unchanged. Our study indicates that tiotropium at higher doses than required for bronchodilation, effectively suppresses inflammation and mucus hypersecretion in the lungs and airways of mice during the initiation and relapse of asthma. Tiotropium is currently not approved for use in asthma. Clinical studies have to demonstrate the efficacy of tiotropium in this respiratory disease.

Differential effects of rapamycin and dexamethasone in mouse models of established allergic asthma

The mammalian target of rapamycin (mTOR) plays an important role in cell growth/differentiation, integrating environmental cues, and regulating immune responses. Our lab previously demonstrated that inhibition of mTOR with rapamycin prevented house dust mite (HDM)-induced allergic asthma in mice. Here, we utilized two treatment protocols to investigate whether rapamycin, compared to the steroid, dexamethasone, could inhibit allergic responses during the later stages of the disease process, namely allergen re-exposure and/or during progression of chronic allergic disease. In protocol 1, BALB/c mice were sensitized to HDM (three i.p. injections) and administered two intranasal HDM exposures. After 6 weeks of rest/recovery, mice were re-exposed to HDM while being treated with rapamycin or dexamethasone. In protocol 2, mice were exposed to HDM for 3 or 6 weeks and treated with rapamycin or dexamethasone during weeks 4-6. Characteristic features of allergic asthma, including IgE, goblet cells, airway hyperreactivity (AHR), inflammatory cells, cytokines/chemokines, and T cell responses were assessed. In protocol 1, both rapamycin and dexamethasone suppressed goblet cells and total CD4(+) T cells including activated, effector, and regulatory T cells in the lung tissue, with no effect on AHR or total inflammatory cell numbers in the bronchoalveolar lavage fluid. Rapamycin also suppressed IgE, although IL-4 and eotaxin 1 levels were augmented. In protocol 2, both drugs suppressed total CD4(+) T cells, including activated, effector, and regulatory T cells and IgE levels. IL-4, eotaxin, and inflammatory cell numbers were increased after rapamycin and no effect on AHR was observed. Dexamethasone suppressed inflammatory cell numbers, especially eosinophils, but had limited effects on AHR. We conclude that while mTOR signaling is critical during the early phases of allergic asthma, its role is much more limited once disease is established.

Clarithromycin suppresses airway hyperresponsiveness and inflammation in mouse models of asthma

Macrolide antibiotics, a class of potent antimicrobials, also possess immunomodulatory/anti-inflammatory properties. These properties are considered fundamental for the efficacy of macrolide antibiotics in the treatment of diffuse panbronchiolitis and cystic fibrosis. In patients with asthma, macrolide antibiotics have been reported to reduce airway hyperresponsiveness and improve pulmonary function. However, their beneficial actions in asthmatics possibly could be attributed to antimicrobial activity against atypical pathogens (e.g. Chlamydia pneumoniae), corticosteroid-sparing effect (inhibition of exogenous corticosteroid metabolism), and/or their anti-inflammatory/immunomodulatory effects. In order to investigate whether efficacy of macrolide antibiotics in asthma results from their immunomodulatory/anti-inflammatory activity, the influence of clarithromycin pretreatment (2 h before challenge) was examined on ovalbumin-induced airway hyperresponsiveness and airway inflammation in the mouse. Clarithromycin treatment (200 mg/kg intraperitoneally) decreased IL-4, IL-5, IL-13, CXCL2 and CCL2 concentrations in bronchoalveolar lavage fluid and markedly reduced inflammatory cell accumulation in bronchoalveolar lavage fluid and into the lungs, as revealed by histopathological examination. Furthermore, clarithromycin-induced reduction in inflammation was accompanied by normalization of airway hyperresponsiveness. In summary, in ovalbumin-induced mouse models, clarithromycin efficiently inhibited two important pathological characteristics of asthma, airway hyperresponsiveness and inflammation. These data suggest that the efficacy of clarithromycin, as well as of other macrolide antibiotics, in asthmatic patients could be attributed to their anti-inflammatory/immunomodulatory properties, and not only to their antimicrobial activity or exogenous corticosteroid-sparing effects.

Effects of umbelliferone in a murine model of allergic airway inflammation

The therapeutic effects of umbelliferone (30, 60 and 90 mg/kg), a coumarin isolated from Typha domingensis (Typhaceae) were investigated in a mouse model of bronchial asthma. BALB/c mice were immunized and challenged by nasal administration of ovalbumin. Treatment with umbelliferone (60 and 90 mg/kg) caused a marked reduction of cellularity and eosinophil numbers in bronchoalveolar lavage fluids from asthmatic mice. In addition, a decrease in mucus production and lung inflammation were observed in mice treated with umbelliferone. A reduction of IL-4, IL-5, and IL-13, but not of IFN-gamma, was found in bronchoalveolar lavage fluids of mice treated with umbelliferone, similar to that observed with dexamethasone. The levels of ovalbumin-specific IgE were not significantly altered after treatment with umbelliferone. In conclusion, our results demonstrate that umbelliferone attenuates the alteration characteristics of allergic airway inflammation. The investigation of the mechanisms of action of this molecule may contribute for the development of new drugs for the treatment of asthma.

The triterpenoid lupeol attenuates allergic airway inflammation in a murine model

Asthma is a chronic inflammatory disease of the airways associated with a Th2 immune response. Despite their side effects, corticosteroids are the most used and effective drugs for treatment of asthma. In this work we investigated the efficacy of lupeol, a triterpenoid isolated from Lonchocarpus araripensis [corrected] Benth. (Fabaceae), in the treatment of bronchial asthma in BALB/c mice immunized with ovalbumin. Administration of lupeol caused the reduction of cellularity and eosinophils in the bronchoalveolar lavage fluid. Treatment with lupeol also reduced the production of mucus and overall inflammation in the lung. Levels of Type II cytokines IL-4, IL-5 and IL-13 were significantly reduced in mice treated with lupeol, an effect that was similar to that observed in dexamethasone-treated mice. In contrast, IgE production was not significantly altered after treatment with lupeol. In conclusion, our results demonstrate that lupeol attenuates the alterations' characteristics of allergic airway inflammation. The investigation of the mechanisms of action of this molecule may contribute for the development of new drugs for the treatment of asthma.

Pioglitazone is as effective as dexamethasone in a cockroach allergen-induced murine model of asthma

Background

While glucocorticoids are currently the most effective therapy for asthma, associated side effects limit enthusiasm for their use. Peroxisome proliferator-activated receptor-γ (PPAR-γ) activators include the synthetic thiazolidinediones (TZDs) which exhibit anti-inflammatory effects that suggest usefulness in diseases such as asthma. How the ability of TZDs to modulate the asthmatic response compares to that of glucocorticoids remains unclear, however, because these two nuclear receptor agonists have never been studied concurrently. Additionally, effects of PPAR-γ agonists have never been examined in a model involving an allergen commonly associated with human asthma.

Methods

We compared the effectiveness of the PPAR-γ agonist pioglitazone (PIO) to the established effectiveness of a glucocorticoid receptor agonist, dexamethasone (DEX), in a murine model of asthma induced by cockroach allergen (CRA). After sensitization to CRA and airway localization by intranasal instillation of the allergen, Balb/c mice were challenged twice at 48-h intervals with intratracheal CRA. Either PIO (25 mg/kg/d), DEX (1 mg/kg/d), or vehicle was administered throughout the period of airway CRA exposure.

Results

PIO and DEX demonstrated similar abilities to reduce airway hyperresponsiveness, pulmonary recruitment of inflammatory cells, serum IgE, and lung levels of IL-4, IL-5, TNF-α, TGF-β, RANTES, eotaxin, MIP3-α, Gob-5, and Muc5-ac. Likewise, intratracheal administration of an adenovirus containing a constitutively active PPAR-γ expression construct blocked CRA induction of Gob-5 and Muc5-ac.

Conclusion

Given the potent effectiveness shown by PIO, we conclude that PPAR-γ agonists deserve investigation as potential therapies for human asthma.

Creatine supplementation exacerbates allergic lung inflammation and airway remodeling in mice

Creatine supplement is the most popular nutritional supplement, and has various metabolic functions and sports medicine applications. Creatine supplementation increases muscle mass and can decrease muscular inflammation. Some studies have also suggested a beneficial role of creatine supplementation on chronic pulmonary diseases such as chronic obstructive pulmonary disease and cystic fibrosis. Among athletes, the prevalence of asthma is high, and many of these individuals may be taking creatine. However, the effects of creatine supplementation on chronic pulmonary diseases of allergic origin have not been investigated. In the present study, we analyzed the effects of creatine supplementation on a model of chronic allergic lung inflammation. Thirty-one Balb/c mice were divided into four groups: control, creatine (Cr), ovalbumin (OVA), and OVA+Cr. OVA and OVA+Cr groups were sensitized with intraperitoneal injections of OVA on Days 0, 14, 28, and 42. OVA challenge (OVA 1%) and Cr treatment (0.5 g/kg/d) were initiated on Day 21 and lasted until Day 53. We determined the index of hyperresponsiveness, the serum levels of OVA-specific immunoglobulin (Ig)E and IgG(1), and the total and differential cell counts in bronchoalveolar lavage fluid. We also quantified airway inflammation, and the airway density of IL-4+, IL-5+, IL-2+, IFN-gamma+, and insulin-like growth factor (IGF)-1+ cells, collagen and elastic fibers, and airway smooth muscle thickness. Our results showed that creatine in OVA-sensitized mice increased hyperresponsiveness; eosinophilic inflammation; airway density of IL-4+, IL-5+, and IGF-1 inflammatory cells; airway collagen and elastin content; and smooth muscle thickness. The results show that creatine supplementation exacerbates the lung allergic response to OVA through a T helper cell type 2 pathway and increased IGF-1 expression.

Are mouse models of allergic asthma useful for testing novel therapeutics?

Experimental mouse allergic asthma is a reliable, clinically relevant facsimile of human disease. The focus here is to demonstrate that antigen-induced mouse allergic asthma is a useful model for testing novel therapeutics. Furthermore, it is especially crucial to treat mice during established disease, either during ongoing clinically manifest disease or to prevent disease relapses. In addition, our results indicate that lung Th2 resting memory cells are important targets for the treatment of allergic asthma.

Dexamethasone inhalations in RSV bronchiolitis: a double-blind, placebo-controlled study

OBJECTIVE

To evaluate the effect of inhaled dexamethasone on hospitalization for respiratory syncytial virus (RSV) bronchiolitis.

STUDY DESIGN

A double-blind, placebo-controlled study compared nebulization of dexamethasone versus nebulization of 0.9% saline. Both groups were treated with epinephrine nebulizations. Follow-up continued for 3 mo.

PATIENTS AND METHODS

Sixty-one infants with bronchiolitis aged 3 to 12 mo were included. They were randomly allocated to nebulizations with 0.25 mg dexamethasone every 6 h (group 1) or an equivalent amount of normal saline (group 2).

RESULTS

No statistically significant differences with respect to clinical score, oxygen saturation, or IV fluid requirement between the groups were noted. Using Kaplan-Meyer's method, the cumulative proportion of in-hospital stay was significantly lower in group 1 compared with group 2, mainly in days 5 and 6 post-hospitalization (p<0.038). A subgroup of prematurely born children in group 1 had a shorter hospitalization period (6.5+/-1.7 d) compared with group 2 children (9.1+/-1.9) (p<0.018). Follow-up revealed similar wheeze and hospitalization rates in the two groups.

CONCLUSION

Inhaled dexamethasone may reduce the length of hospitalization among infants with acute viral bronchiolitis, especially among those born prematurely.