[Use of the mouse to unravel allergic asthma: a review of the pathogenesis of allergic asthma in mouse models and its similarity to the condition in humans]

A new combination therapy for asthma using dual-function dexamethasone-conjugated polyethylenimine and vitamin D binding protein siRNA

Asthma is a multifactorial disease that is influenced by the interaction of genetic and environmental factors. Because of its complex nature, there is no cure for asthma currently. Instead, reliever and controller medications are used to treat asthma. Unfortunately, conventional treatments do not work in some severe cases of asthma. In addition, there may be adverse, systemic effects of long-term treatment with high-dose inhaled corticosteroids (ICSs) as a controller medication. Therefore, we attempted to develop a novel combination therapy for asthma. Our regimen included dexamethasone as a controller medication and vitamin D binding protein (VDBP) small interfering RNA (siRNA) as a novel target therapeutic. The dexamethasone moiety of DEXA-PEI (dexamethasone-conjugated polyethylenimine) was used as an ICS, combined with anti-VDBP treatment via delivery of VDBP siRNA, using DEXA-PEI as a siRNA carrier molecule. Treatment with DEXA-PEI/VDBP siRNA effectively reduced the ovalbumin sensitization/challenge-induced enhancement of airway inflammation, goblet cell hyperplasia and expression of interleukin (IL)-4, IL-13 and CCL11. These findings suggest that the DEXA-PEI/VDBP siRNA can be developed as a potent asthma therapeutic by dose-reducing ICSs and using a multitarget therapeutic method.

A, Zhang S, Xue Q, Xie X, Lu S. TLR3 and TLR7 modulate IgE production in antigen induced pulmonary inflammation via influencing IL-4 expression in immune organs

Background

Toll-like receptors (TLRs) as pattern recognition receptors, participate in both innate and adaptive immune responses, and seem to play an important role in the pathogenesis of asthma. This study aimed to identify key TLRs involved in antigen induced pulmonary inflammation (AIPI), a rat model for asthma, and to explore the role of TLRs in the disease development.

Methods and Findings

E3 rats were sensitized with ovalbumin (OVA)/alum intraperitoneally and intranasally challenged with OVA to induce AIPI model. TLR1-9 and cytokine mRNA expression in spleen, lung and mediastinal lymph node (mLN) tissues were screened by quantitative real-time polymerase chain reaction. TLR7 expression was found to be significantly down-regulated in spleen while TLR3 and TLR8 expression was up-regulated in mLN of AIPI rats. Furthermore, imiquimod (a ligand of TLR7) and TLR3 specific short-hairpin RNA plasmid for RNA interference were administrated, respectively, in vivo to AIPI rats to observe their effects on the disease by assessing various asthmatic parameters. The numbers of total cells, eosinophils, macrophages and lymphocytes were counted according to differential morphology in bronchoalveolar lavage fluid. Serum IgE and OVA specific IgG₁ concentration was detected by enzyme-linked immunosorbent assay. The results showed that both TLR7 ligand treatment and TLR3 RNAi in vivo decreased serum IgE level and interleukin-4 mRNA expression.

Conclusion/Significance

TLR3 in mLN and TLR7 in spleen both systemically modulate disease development in AIPI rats via altering serum IgE concentration relevant to Th2 responses. And these findings may provide an important clue for further research in the asthma pathogenesis and suggest a new remedy for asthma treatment.

Increased muscarinic receptor activity of airway smooth muscle isolated from a mouse model of allergic asthma

The mechanisms leading to airway hyper-responsiveness (AHR) in asthma are still not fully understood. AHR could be produced by hypersensitivity of the airway smooth muscle or hyperreactivity of the airways. This study was conducted to ascertain whether AHR in a murine model of asthma is produced by changes at the level of the airway smooth muscle. Airway smooth muscle responses were characterised in vitro in isolated trachea spirals from naive mice and from an acute ovalbumin (OVA) challenge model of allergic asthma. AHR was investigated in vivo in conscious, freely moving mice. Inflammatory cell influx into the lungs and antibody responses to the antigen were also measured. In vitro study of tracheal airway smooth muscle from naïve mice demonstrated concentration-related contractions to methacholine and 5-HT, but no responses to histamine or adenosine or its stable analogue, 5'-N-ethyl-carboxamidoadenosine. The contractions to 5-HT were inhibited by ketanserin and alosetron indicating involvement of 5-HT(2A) and 5-HT(3) receptors, respectively. In an acute model of allergic asthma, OVA-treated mice were shown to be atopic by inflammatory cell influx to the lungs after OVA challenge, increases in total IgE and OVA-specific IgG levels and contractions to OVA in isolated trachea. In the asthmatic model, AHR to methacholine was demonstrated in conscious, freely moving mice in vivo and in isolated trachea in vitro 24 and 72h after OVA challenge. No AHR in vitro was seen for 5-HT, histamine or adenosine. These results suggest that, in our mouse model of asthma, changes occur at the level of the muscarinic receptor transduction pathway of coupling to airway smooth muscle contraction. These changes are maintained when tissues are removed from the inflammatory environment and for at least 3 days.

Immunization with live influenza viruses in an experimental model of allergic bronchial asthma: infection and vaccination

BACKGROUND

Asthmatics in particular have a need for influenza vaccines because influenza infection is a frequent cause of hospitalization of patients with bronchial asthma. Currently, only inactivated influenza vaccines are recommended for influenza prevention in asthma sufferers.

OBJECTIVE

The aim of our study was to analyze and compare the effects of influenza infection and vaccination with live attenuated influenza vaccine (LAIV) on different phases of experimental murine allergic bronchial asthma (acute asthma and remission phase) and on subsequent exposure to allergen in sensitized animals.

METHODS

Ovalbumin (OVA)-specific serum IgE levels, IL-4 production by spleen and lung lymphocytes, and histological changes in the lungs of mice infected with pathogenic virus or LAIV were studied at two phases of OVA-induced bronchial asthma (acute asthma and remission). Results Infection with pathogenic virus both in acute asthma and remission led to asthma exacerbation associated with the production of OVA-specific IgE, IL-4 and significant inflammatory infiltration in airways. Infection, even after complete virus clearance, induced the aggravation of lung inflammation and IgE production in asthmatic mice additionally exposed to OVA. Immunization with LAIV at remission did not enhance allergic inflammatory changes in the lung, OVA-specific IgE or IL-4 production. Then after additional OVA exposure, histological and immunological changes in these mice were the same as in the control group.

CONCLUSIONS

Influenza infection provokes asthma exacerbation regardless of the disease phase. Immunization with LAIV during the remission phase of bronchial asthma is safe and does not interfere upon subsequent contact of asthma sufferers with allergen.

Study of a BALB/c Mouse Model for Allergic Asthma

Allergic asthma is a worldwide public health problem and a major socioeconomic burden disease. It is a chronic inflammatory disease marked by airway eosinophilia and goblet cell hyperplasia with mucus hypersecretion. Mouse models have proven as a valuable tool for studying human asthma. In the present report we describe a comparison of mouse asthma models. The experiments were designed as follows: Group I was injected with ovalbumin (OVA, i.p.) on day 1 and challenged with 1% OVA (aerosol exposure) on days 14~21. Group II was injected on day 1, 14 and aerosol-immunized on days 14~21. Group III was injected on day 1, 14 and immunized by 1% OVA aerosol on days 18~21. We assessed asthma induction by determining the total number of white blood cells (WBC) and eosinophils as well as by measuring cytokine levels in bronchoalveolar lavage fluid (BALF). In addition, we evaluated the histopathological changes of the lungs and determined the concentration of immunoglobulin E (IgE) in serum. Total WBC, eosinophils, Th2 cytokines (IL-4, IL-13) and IgE were significantly increased in group I relative to the other groups. Moreover, histopathological studies show that group I mice show an increase in the infiltration of inflammatory cell-in peribronchial and perivascular areas as well as an overall increase in the number of mucus-containing goblet cells relative to other groups. These data suggest that group I can be a useful model for the study of human asthma pathobiology and the evaluation of existing and novel therapeutic agents.