Functional Characterization of Peroxisomes and Peroxisome Proliferator Activated Receptor-Gamma in the Chicken Respiratory System
Mutua, Patrick Mbuvi
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Poultry farming supports over twenty one million farmers and is the lead livestock enterprise sector poised to alleviate abject poverty and improve food security in Kenya. However, growth of the sector is constrained by high mortality and morbidity associated with various disease conditions of the respiratory system. Avian respiratory disease conditions are characterized by acute inflammation of the respiratory epithelia which is useful in localization of the injurious stimuli and initiation of tissue healing process. However, prolonged inflammation which is partly characterized by secretion of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-a) and release of reactive oxygen (ROS) and nitrogen species (RNS),. is maladaptive and is known to promote disease and tissue destruction. In mammals, peroxisome enzymes such as catalase, the major antioxidant peroxisome enzyme, are involved in inflammatory resolution through degradation of ROS and RNS. Furthermore, peroxisome proliferatoractivated receptor-gamma (PPAR-y), a ligand activated transcription factor, is present in the mammalian respiratory epithelial cells and alveolar macrophage and participates in inflammatory resolution by inhibiting release of proinflammatory cytokines from activated airway epithelia and alveolar macrophage and by upregulating phagocytic capacity of respiratory macrophages. Use of synthetic antioxidants to supplement or stimulate production of endogenous antioxidants requires knowledge of cellular location of the endogenous antioxidants. Catalase content in peroxisomes varies between species, organs and age of members of a species. The cellular location of catalase and antiinflammatory roles of PPAR-y in the avian respiratory tract are not known. This study seeks to identify peroxixomes as the cellular location of catalase and evaluate antiinflammatory roles of PPAR-y in the chicken respiratory system. Fixation of the chicken respiratory system will be followed by cytochemical localization of peroxisome in the avian respiratory using 3, 3'diaminobenzidine (DAB) method. Morphologic examination of the peroxisome will be done at light and electron microscopy. Quantification of catalase in the chicken respiratory system will be determined by immunohistochemical techniques. Using troglitazone, a synthetic PPAR-y ligand, investigation of inhibitory effects of PPAR-y on secretion of proinflammatory cytokine by free avian respiratory macrophages (FARM) properties will be evaluated by measuring TNF-a using ELISA test. Effects of activated PPAR-y on phagocytic capacity of FARM will be determined by performing phagocytic assay using polystyrene particles. To recover sufficient FARM, chicken will be subjected to five lavage processes. The work will be conducted in the Department of Zoological Sciences. Kenyatta University. A total of 48 chickens will be used in the study. Group data for multiple comparisons will be analyzed by ANOYA followed by Duncan's multiple range test to test for differences. The level of significance will be set at p ::::0.05 confidence levels. Data generated would inform potential design of antioxidant therapeutics targeting catalase and potential use of synthetic PPAR-y ligands in treatment and management of respiratory disease conditions of the domestic birds.