الفهرس 
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Abstract
In western industrialized countries, bronchial asthma prevalence is rising by about 5% per year with about half a million new cases of asthma in children in the United States every year. The effect of helminth infection on allergic disorders such as bronchial asthma and on autoimmune diseases has been studied thoroughly in the past years. These studies were based on the fact that helminths evade the immune system of the host to ensure their survival for years in the host. Several epidemiological studies have mentioned that infections with some helminths such as Schistosoma mansoni and Brugia malayi are accompanied with reduced allergic symptoms which could be a promising mode of therapy to treat allergic and autoimmune diseases including inflammatory bowel disease, autoimmune encephalomyelitis, arthritis and allergic asthma. Furthermore, there is little information concerning the effect of infection with the parasitic nematode Trichinella spiralis on bronchial asthma. Thus, this work was planned to find out the effect of infection with Trichinella spiralis on asthma in asthma mouse model. In order to fulfill this aim, mice were chosen as a bronchial asthma animal model in this work because most hallmarks of human asthma can be induced in mice. This study was conducted on 120 male Swiss albino mice divided into four main groups: group I (normal control group), group II (asthma control group), group III; a preventive group and it was divided into two subgroups:- Subgroup IIIa and IIIb were infected with 100 and 200 T. spiralis muscle larvae/mouse respectively and both were sensitized on the 28th day P.I. group IV was a therapeutic group and was further divided into Subgroup IVa and IVb which were infected with 100 and 200 T. spiralis muscle larvae/mouse respectively and sensitized on the 10th day P.I. Sensitized mice received two intra-peritoneal injections, on days 0 and 7 in a dose of 100 μg of ovalbumin in 200 μl of 0.9 % sterile saline adsorbed to 1 mg of aluminum hydroxide as adjuvant. For challenge, 50 μg of ovalbumin was intranasally administered in a total volume of 50 μl of sterile saline to the mice on days 14, 16. The animals were sacrificed using the approved methods of euthanasia at the 18th day of sensitization. All euthanized mice were submitted to the following procedures: • Histopathological study by H & E staining for the lung tissues. • Immunohistochemical study of lung tissues for FOXP3+ CD4+ T cells expression were done. • Measuring differential leukocytic count in bronchoalveolar lavage fluid and in blood for all the studied groups. • Measuring levels of IL-6, IL-13 and IL-10 in lung tissue homogenates was done by ELISA technique. from the previous work, the following results were obtained: 1- Histopathological examination of the lung tissues of T. spiralis infected groups showed significant reduction of peribronchial and perivascular inflammatory cell infiltrates compared with asthma group. 2- By immunohistochemical examination, there was a significant difference in the expression of FOXP3+CD4+ T cells among the studied groups. The preventive group showed strong to moderate FOXP3+ CD4+ T cells expression compared with the induced asthma group. The therapeutic groups also showed moderate FOXP3+ CD4+ T cells expression. 3- Leukocytic counts in blood of induced asthma group showed significant increase compared with the normal control group with significant elevation in eosinophils compared with the normal control group. Lymphocytes, neutrophils, and monocytes in the asthma group were also significantly higher than in the normal control. 4- The preventive group showed significantly reduced total leucocytic counts compared with the induced asthma group. Eosinophil counts were significantly reduced in the preventive and therapeutic groups compared with asthma group. 5- Differential count of leucocytes in the bronchoalveolar lavage fluid revealed that infection with T. spiralis after OVA sensitization in group III and IV resulted in a significant decrease in the number of eosinophils compared with mice that were OVA sensitized only. 6- The induced asthma group showed significant elevation of IL-6 & IL-13 levels and IL-10 levels compared with the normal control group. 7- Levels of IL-6 and IL-13 showed significant reduction in the preventive and therapeutic groups. On the other side, levels of IL-10 showed significant elevation in the infected groups compared with the asthma control group.