Excess fibrosis, in both liver (cirrhosis) and extrahepatic tissues (i.e. lungs), leads to devastating end-stage diseases with high morbidity and mortality. Presently, no effective treatment is available. The purpose of the proposed research is to establish dilinoleoylphosphatidylcholine (DLPC) as an effective, safe, and chemically defined therapeutic agent, clarify its mode of action and codify its proper use. The investigator previously observed that polyenylphosphatidylcholine (PPC) extracted from soybeans fully prevents alcohol-induced cirrhosis in non-human primates. DLPC is the main phospholipid species of PPC and, based on preliminary experiments, it is presumably its active component, but this far the high cost of the purified compound precluded any appreciable in vivo use. However, less expensive synthetic DPLC is now available to the investigator. This pure preparation will be tested in vivo and in vitro to firmly establish that it is indeed the active phospholipid species of PPC. The extent and mechanisms of the antifibrotic effect of DLPC and PPC will be studied in liver fibrosis, as well as cirrhosis induced by CC14 or heterologous albumin in rats. For pulmonary fibrosis, a silica dust rat model will be used. The investigations will include the assessment of the relative role of decreased collagen synthesis and enhances collagen breakdown in the prevention of fibrosis. In addition, experiments will be conducted on the reversal of preexisting fibrosis. alpha 1 (I) procollagen will be determined and collagen breakdown will be measured by the activity (and mRNA) of metalloproteinase 1 and collagenase inhibitors such as tissue inhibitors of metalloproteinases (TIMPs). Studies will also be carried out in cultured lipocytes and/or in lipocytes co-cultured with Kupffer cells or hepatocytes. The same systems will be used to ascertain whether DLPC and PPC affect fibrogenic cytokines such as TGF-Beta, TNF-alpha and IL-6. Agents which oppose oxidative stress, such as S-adenosylmethionine (SAMe) or vitamin E, and possibly anticytokines, will be studied to determine whether they potentiate the beneficial effects of DLPC or PPC. To ascertain the optimal time for initiation of treatment, one will evaluate, in available, routinely obtained clinical specimens, the diagnostic value for detecting precirrhotic lesions in non-invasive tests, such as measurements of circulating tissue inhibitor of metalloproteinases (TIMP-1) and procollagen peptides (PIIIP). If successful, the proposed studies will establish DLPC as the first safe and chemically defined agent capable of preventing the progression (and possibly of promoting the regression) of hepatic and pulmonary fibrosis.
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