The initiation and maintenance of chronic pulmonary inflammation is due to a dynamic interaction between an inciting agent, inflammatory mediators, leukocytes, and structural cells of the lung. Clinically, the therapeutic modalities that are available to treat granulomatous lung diseases are limited, which reflects the level of understanding of these diseases. Treatment of infectious granulomatous diseases has usually targeted the etiologic agent, while treatment of idiopathic lung disease has usually possess a similar pathologic response, which is characterized by the elicitation and activation of various leukocyte populations to a defined area of the lung. Studies directed at understanding the cellular and molecular mechanisms which are responsible for the recruitment and activation of leukocytes during the initiation and maintenance phases of the granulomatous response are the broad, long-term objectives of this application. The working hypothesis of this proposal is the following: the initiation and maintenance of a delayed type hypersensitivity (DTH) reaction in the lung is dependent upon the expression of early response cytokines which initiates a cascade of events resulting in the expression of specific adhesion molecules necessary to first localize leukocytes to the lesion and then to activate leukocytes for the expression of chemotactic cytokines needed to recruit cells into the developing granuloma. This hypothesis will be addressed by focusing on three interrelated areas of investigation: 1) the contribution of interleukin-1 (IL-1) and tumor necrosis factor (TNF), and the regulation of their biologic activity by the IL-1 receptor antagonist (IRAP) and a soluble TNF receptor during lung granuloma development; 2) the contribution of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), as mediators which initially localize leukocytes to the granulomatous lesion and subsequently activate leukocytes during the evolution of the DTH response; and 3) the contribution of the chemotactic cytokine, macrophage inflammatory protein-1 alpha (MIP-1), to the developing granuloma. Experimental models of lung granulomatous inflammation will be utilized to assess the interactions between early response cytokines, adhesion molecules and the generation of MIP-1. DTH and foreign body lung granuloma models will be studied for the effects of IRAP, sTNFr;Fc, and specific neutralizing antibodies to ICAM-1, VCAM- 1, and MIP-1 on the developing lesions. A number of techniques will be employed in this application, including the use of Northern blot, reverse transcription-polymerase chain reaction (RT-PCR), mRNA stability, and in situ hybridization analyses for studying the regulation of specific polypeptide gene expression; the use of immunohistochemistry for antigen localization and ELISAs for the quantitation of cytokines and endogenous mediators of cytokine activity; and bioassays for assessing functional activities of specific mediators.
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