Study On The Role Of Airborne Fungi And Dust Mites In Induction Of Asthma

The prevalence of asthma has been increasing dramatically in recent decades in western world and populous metropolis in china.Then asthma has been the major public health issue in world.It can be considered that the most significant inhaled agents that regulate the development of respiratory allergy and asthma are biologics. And airborne fungi and dust mites are the two most important biological risk factors which have been the critical domain of asthma research.The aim of this subject is to find the possible pathogenic mechanisms of asthma induced by dust mites and fungi through animal experiments in vivo.The possible risk factors of asthma patients and their distribution in asthma patients will be studied through epidemiologic methods.The first part in our study,Alternaria alternate was cultivated in substrate and its spores were collected.Different kinds of air-carried spores of fungi were collected by placing the sampling substrate in the open air and the spores were cultivated, separated,inoculated and identified,then the spores of Alternaria alternate were obtained.A great deal of pure spore suspensions were harvested through cultivated the Alternaria alternate.At last the concentrations of spores' suspension were adjusted to 4×10~7/mL and 4×10~6/mL separately.The objective of the second part of this study was to develop a method of establishment of airway allergic inflammation model of C57BL/6 mice sensitized and challenged with the spores of Alternaria alternate.The total 36 C57BL/6 mice were divided into negative control,positive control and model groups,twelve mice in each group.Mice of model group were sensitized with spores at day 0,5,10 by intraperitoneal(i.p.) injection,and challenged four times by intranasal(i.n.) drip from day 14 to day 17.OVA instead of spores were used in the positive control group,PBS used in the control group.Bronchoalveolar lavage fluid(BALF) was taken at 24h after the last tine of challenge,and the pathological manifestation of the lung,cell counts and differential count and IL-4,IFN-γ,total protein levels in BALF were assessed.The levels of total IgE and specific IgE in plasma were identified,the airway resistance and lung compliance were determined.The results indicate that there was pulmonary eosinophilic inflammation in the positive control and model groups.Total cells count,differential cells count and IL-4 and total protein levels in BALF were enhanced significantly while IFN-γdeclined remarkably.The levels of total IgE and specific IgE were increased remarkably in plasma in positive control and model groups,the airway resistance was enhanced and lung compliance decreased. An airway allergic inflammation model of C57BL/6 mice has been established by sensitizing and challenge with spores of Alternaria alternate.In the third part of this study,the objective was to observe the effects of the dermatophagoides farinae(Derf) allergen on the mice model of asthma.The 48 C57BL/6 mice were divided into control,asthma,Deft intranasal control and Derf intranasal asthma group,twelve mice in each group.Mice of asthma group were sensitized with spores at day 0,5,10 by intraperitoneal injection,and challenged four times by intranasal drip from day 14 to day 17,and then mice were instilled i.n.with PBS in 30 minutes.Derf instead of PBS was used in the Derf intranasal asthma group and the procedure of sanitization and challenge was same as asthma group,PBS used in the control group from the sensitization,challenge and instilment,then Derf instead of PBS was used in Derf intranasal control group in the phase of instilment,the other procedure same as control group.BALF was taken at 24h after the last time of instilment,and the pathological manifestation of the lung,cell counts and differential count and total protein levels in BALF were assessed.The airway resistance and lung compliance were determined.The results show that there was significant difference on cell count between Derf intranasal asthma group and asthma group.Pulmonary eosinophilic inflammation was found in all groups except control group.In the forth part of this study,an epidemiological study has been carried out about environmental risk factors of Children asthma.The distribution of common allergens in asthma children were identified for the sake of recognized the most important allergens.It was clear that the positive rate of dermatophagoides farinae was no.1 through skin prick tests in asthma children,the rate was 51.2%.The information of asthma children in general socio-demographic characteristics,allergic history,family history and indoor environmental was collected through a hospital-based case-control study,so that some risk factors were identified.After control of possible confounding factors,it was found that parents history of asthma, children history of allergy and children respiratory tract infection were risk factors for childhood asthma.The results suggest that there is need for our country especially at populous city to enhance asthma disease reporting system.It's necessary to carry out exposure assessment on indoor fungi,home dust mite and et cetera.It is significant to research the environmental risk factors for childhood asthma and mechanism of nosogenesis, then develop new and effective methods on environmental control and therapy for asthma to maximizing the cure rate and controling the asthma occurrence.