Dexamethasone and budesonide groups exhibited significant protein and mRNA reductions in IL-25, as compared with the asthma group after excitation (P<0.05), whereas these two groups significantly increased levels compared with the normal group after excitation (P<0.05).
IL-25, an IL-17 family cytokine, was recently reported to induce TH2-type immune responses and to contribute to several allergic diseases, such as atopic dermatitis and asthma.
Compared with that in asthma models, SIT administration decreased (1) airway hyper-responsiveness; (2) the production of cytokines, including IL-4, IL-5, IL-13, and IL-25, as well as serum HDM-specific IgE and IgG1, as shown by ELISA; and (3) lipid oxidative species, such as reactive oxidative species (ROS) and malondialdehyde (MDA), in the lung tissue.
Clinical trials support a central role for TSLP in driving airway inflammation and asthma exacerbations, while ongoing trials blocking IL-33 and IL-25 will help to define their respective role in asthma.
IL-25 played an important role in these models of asthma because IL-25 receptor-deficient mice did not develop disease after sensitization and challenge with allergen.
Further work is required to develop human monoclonal antibodies (hMabs) directed against IL-25 and IL-33 or their receptors, to help understand their role in the initiation and/or persistence of asthma.
Emerging data now suggest that epithelial cell-derived cytokines such as thymic stromal lymphopoietin (TSLP), IL-33, and IL-25 may drive the progression from atopic dermatitis to asthma and food allergy.
Whether the blockade of PI3K signalling directly inhibits the asthma relevant pathogenetic changes induced by IL-25 in an in vivo condition is still unclear.
Recent studies clearly show that not only Th2 cytokines but also other T cell-related cytokines such as IL-17A and IL-22 as well as epithelial cell cytokines such as IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) are involved in the pathogenesis of asthma.
Stimulation with IL-33 alone induced a significantly greater quantity of IL-13 by Lineage-cells from mugwort-allergic asthmatic compared with that from HDM-allergic asthmatics, whereas IL-25 induced a significantly greater amount of IL-5 by the Lineage-cells from mugwort-allergic asthmatic compared with that from HDM-allergic asthmatics.
Our findings suggest that IL-25 is elevated in asthma and contributes to angiogenesis, at least partly by increasing endothelial cell VEGF/VEGF receptor expression through PI3K/Akt and Erk/MAPK pathways.
The function of IL-25 in allergic diseases such as asthma has been well established, and now also is extended to diseases such as inflammatory bowel disease and cancer.
In addition, IL-25 neutralisation abrogated peribronchial collagen deposition, airway smooth muscle hyperplasia and airway hyperreactivity in control mice exposed to HDM and smad2-overexpressing mice.
These results suggest that the combined inhibition of IL-13 and IL-25 may provide a novel therapeutic strategy for asthma, especially for patients who are resistant to current treatments.
The FeNO levels were significantly correlated with the peripheral blood eosinophil counts (r = 0.430, p = 0.001) and serum IL-25 concentrations (r = 0.338, p = 0.009) in patients with asthma.
We investigated the time course of ILC2 accumulation in different tissues in murine models of asthma induced by a serial per-nasal challenge with ovalbumin (OVA), house dust mice (HDM), IL-25 and IL-33 and explored the potential roles of ILC2-attracting chemokines in this phenomenon.
The concentrations of IL-33 and TSLP, but not IL-25, correlated inversely with the lung function (forced expiratory volume in the first second) of asthmatics (IL-33: <i>r</i> = -0.488, <i>p</i> < 0.0001; TSLP: <i>r</i> = -0.565, <i>p</i> < 0.0001) independently of corticosteroid therapy.