The major objective of this project is to gain an understanding of the presently undefined relationship between pulmonary macrophages, lung inflammation and respiratory mucus secretion. Our approach towards achieving this objective will make use of the novel mucus secretagogue, MMS, which is elaborated by pulmonary macrophages, peripheral blood monocytes and a human macrophage hybridoma cell line, (HB63). MMS has been demonstrated to be a mediator of lung inflammation and a regulator of mucus secretion. A further in-depth study of this secretagogue at the molecular level is proposed which will lead to a clearer understanding of the regulatory mechanisms in the biosynthesis and secretion of MMS.
The specific aims are 1) to isolate and sequence the cDNA coding for the MMS protein and to study the pattern of gene expression in cultured cells in response to various inducers and inhibitors of mMS formation and secretion. Gene expression will be studied by measuring steady state mRNA levels in the cells to ascertain whether cellular mRNA is modulated under conditions which exhibit modulation of secreted MMS. Results of these studies will help to elucidate the relationship between MMS secretion and mucus secretion/hypersecretion. Another major objective is to better understand the clinical role that MMS plays in lung diseases associated with mucus hypersecretion as well as to gain an understanding to the mechanism of action of MMS in the secretory cells.
Specific aims two and three are proposed to achieve these goals: 2) to correlate the in-vitro studies with clinical studies by using peripheral blood monocytes from normal volunteers and from patients with inflammatory lung diseases, especially asthmatics, steroid dependent asthmatics and bronchitics and to determine whether there is any relationship between the disease state, levels of MMS and the levels of MMS-mRNA in these cells. 3) to study the mechanism of MMS activity by investigating membrane, transmembrane and cellular signaling pathways associated with MMS stimulation of mucus secretion from the secretory cells. This multifaceted approach should provide new insights into the mechanisms regulating MMS synthesis and secretion, its possible mechanism of action, as well as provide new information about the regulation of mucus secretion in inflammatory lung diseases. In the future, this proposed research may also help in the possible development of diagnostic tools (e.g. RFLP analysis for potential familial predisposition for the development of asthma or steroid dependent asthma), and/or therapeutic agents (e.g. development of new drugs or new use of existing ones) for these diseases.
