The Role of Neurotrophin in a Murine Model of House Dust Mite Induced Allergic Rhinitis

Allergic rhinitis (AR) is an airway hyper-responsiveness (AHR) and mucosal inflammation disease mediated by IgE-associated processes that is characterised by sneezing, nasal congestion, and rhinorrhea. The imbalance of Th1/Th2 immune response is considered to contribute to allergic diseases, however the interval between inflammation and AHR remains unclear. Growing information illustrated that nerve growth factor (NGF), a neurotrophin, plays an important role in neuroimmune interactions by augmenting an existing Th2 immune response. Since probiotics and biocompatible water-soluble chitosan (WSC) have been demonstrated to have anti-inflammatory properties that could inhibit the development of allergic Th2 response, we aim to assess the effect of WSC and probiotic extracts on NGF in Dermatophagoides pteronyssinus (Der p)-induced AR murine model. Intranasal administration of both WSC and probiotic extracts attenuated AHR in Der p-challenged mice due to a lower respiratory resistance and improved the nasal congestion by manifestation higher respirator rate than non-treated mice. Under management of both WSC and probiotic extracts, the thickness of nasal respiratory epithelium was reduced in microscopy. Both of WSC and probiotic extracts treatment moderated allergic inflammation including a decreased level of total and Der p-specific IgE in the serum, lowered expressions of IL-4, IL-5, and IL-13 in nasal lavage fluid, as well as less eosinphil infiltration in the nasal cavity. In particular, therapeutics with both treatments reduced NGF performance in nasal lavage fluid along with its receptors, p75NTR and TrkA, in the respiratory epithelium of nasal mucosa in Der p-stimulated mice.  We suggested that the reduced NGF and its receptor levels may correspond to a decrease in AHR and mucosa inflammation by both WSC and probiotic extracts treatment.