Growth factor-and cytokine-induced vascular smooth muscle cell proliferation, migration, hypertrophy, and matrix production have been shown to play important roles in the development of vascular disorders such as atherosclerosis, hypertension, and restenosis. Growth factors such as angiotensin II (AngII) 1 and platelet-derived growth factor (PDGF) activate intracellular phospholipases, leading to the formation of arachidonic acid, which can be further metabolized by cyclooxygenases, cytochrome P-450 oxygenases, and lipoxygenases (1). Lipoxygenase (LO) action leads to the formation of oxidized lipids such as 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE). LOs and their products of arachidonic acid and linoleic acid metabolism have been shown to mediate growth factor effects in vascular smooth muscle cells (VSMCs) as well as responses to vascular injury. Lipoxygenases are classified as 5-, 8-, 12-, and 15-lipoxygenases based on their ability to insert molecular oxygen at the corresponding carbon atom of arachidonic acid. Three major isoforms of 12-LO have been cloned. They are platelet-type 12-LO, leukocyte-type 12-LO, and epidermis-type 12-LO. These proteins are products of distinct genes and vary in tissue distribution (2, 3).Leukocyte 12-LO has been cloned from porcine and mouse leukocytes (4, 5). The presence of leukocyte-type 12-LO (also termed 12/15-LO) has also been demonstrated in various cell types and tissues, including VSMCs, adrenal cells, rat brain, and kidney (6 -11). Studies from this and other laboratories (12-21) have implicated the leukocyte-type 12-LO pathway in the pathogenesis of atherosclerosis and restenosis. 12-LO expression was demonstrated in atherosclerotic lesions (12). In vascular and mononuclear cells, growth factors and cytokines as well as high glucose stimulate both the activity and expression of 12-LO (6, 13-15). Furthermore, expression of 12-LO protein and mRNA is markedly increased in neointima of balloon-injured rat carotid arteries, and pretreatment with LO inhibitors reduces the rate of neointimal thickening in this model (16,17). We have demonstrated that treatment with a chimeric DNA-RNA hammerhead ribozyme targeted to cleave rat leukocyte-type 12-LO mRNA significantly reduces neointimal thickening in balloon-injured rat arteries (18). We have

Objective. Glomerular mesangial cells are active participants in the pathogenesis of lupus glomerulonephritis (GN). Thus, targeted delivery of therapeutic agents to mesangial cells would be an attractive approach to treatment. However, lack of known unique mesangial cell surface markers has hampered this process. This study was undertaken in a mouse model of lupus GN to identify mesangial markers and to develop a system for targeted drug delivery to the glomerulus.Methods. Based on previous observations, ␣8 integrin expressed on the surface of glomerular mesangial cells was selected as a target molecule for delivery. Two mouse strains susceptible to lupus GN, NZM2328 and (NZM2328 ؋ NOD)F 1 , were studied. Glomerular expression of ␣8 integrin in normal and nephritic mice was confirmed by immunofluorescence and quantitative polymerase chain reaction analysis. Liposomes were formulated and conjugated with an anti-␣8 integrin antibody. These immunoliposomes were loaded with DiI, a red fluorescent dye, to allow tracking in vivo, and injected into the tail vein of female mice at different ages. Specificity of targeting was studied by fluorescence microscopy and flow cytometry.Results. Expression of ␣8 integrin was observed in the glomeruli of normal and nephritic mice. Anti-␣8 integrin immunoliposomes were detected in the glomerulus and glomerular mesangial cells after tail vein injection in normal and nephritic mice. Delivery of DiI by anti-␣8 integrin immunoliposomes was tissue specific, being observed predominantly in the glomeruli, with some nonspecific uptake by CD11b cells.Conclusion. These findings are the first demonstration of specific delivery of anti-␣8 integrin immunoliposomes to the mesangium following tail vein injection in mice. Anti-␣8 integrin immunoliposomes thus offer a novel approach for targeted drug therapy in lupus and other glomerular diseases.

12͞15-Lipoxygenase (LOX) activity is elevated in vascular diseasesarachidonate ͉ linoleate ͉ hypertension ͉ atherosclerosis

Insulin resistance (IR) is associated with an increased risk of cardiovascular diseases. The obese Zucker rat (ZR) is a model of IR that shows markedly increased insulin and triglyceride concentrations without major changes in glucose. In this study, we evaluated the response of obese and lean ZR to carotid balloon injury and determined potential mechanisms and treatments. The neointima-to-media ratio of obese ZR was greater than that of lean ZR, starting at 14 days after injury, and persisted until at least day 30. An enhanced inflammatory response to balloon injury in the obese ZR was reflected by significantly higher ED1-positive macrophage cells in the injured vessel wall compared with that in lean ZR at 3, 7, and 14 days after balloon injury. Inflammatory mediators 12-lipoxygenase (12-LO) and STAT4 were studied in neointimal lesions. Expression of 12-LO RNA was increased beginning at day 7 and showed increases of 4.3-fold on day 14 and 7-fold on day 30 in obese ZR compared with lean animals. Staining of phosphorylated STAT4 (PSTAT4), the activated form of STAT4, in lesions from obese ZR was also increased compared with that in leans. We tested the effects of a novel anti-inflammatory agent, lisofylline (LSF), in the obese ZR. LSF markedly reduced neointimal formation in the obese ZR. LSF also reduced monocyte/macrophage infiltration into the vessel wall and the activation of PSTAT4. These studies suggest both the presence of an exaggerated injury response in the insulin-resistant obese ZR model and that inflammation plays a major role in mediating neointimal growth.