Protein kinase C-delta mediates adventitial cell migration through regulation of monocyte chemoattractant protein-1 expression in a rat angioplasty model.

OBJECTIVE: The adventitia is increasingly recognized as an important player during the development of intimal hyperplasia. However, the mechanism of adventitial cell recruitment to the subintimal space remains largely undefined. We have shown previously that gene transfer of protein kinase C-delta (PKCδ) increases apoptosis of smooth muscle cells following balloon injury. In the current study, we investigated a potential role of PKCδ in regulating the recruitment of adventitial cells. METHODS AND RESULTS: Conditioned media from PKCδ-overexpressing smooth muscle cells stimulated migration and CCR2 expression of adventitial fibroblasts through a MCP-1 dependent mechanism. Following balloon injury of rat carotid arteries, overexpression of PKCδ in smooth muscle cells significantly increased MCP-1 and CCR2 expression and the number of adventitia-originated cells detected in the neointima. Administration of an anti-MCP-1 antibody markedly diminished the recruitment of adventitial cells. Combined PKCδ overexpression and anti-MCP-1 inhibited intimal hyperplasia more effectively than either approach alone. CONCLUSIONS: Our data suggest that PKCδ regulates recruitment of adventitial cells to the neointima via a mechanism involving upregulation of the MCP-1/CCR2 signaling axis in injured arteries. Blockage of MCP-1 while enhancing apoptosis may serve as a potential therapeutic strategy to attenuate intimal hyperplasia.

Restenosis Inhibition and Re-differentiation of TGFß/Smad3-activated Smooth Muscle Cells by Resveratrol.

To date, there is no periadventitial drug delivery method available in the clinic to prevent restenotic failure of open vascular reconstructions. Resveratrol is a promising anti-restenotic natural drug but subject to low bioavailability when systemically administered. In order to reconcile these two prominent issues, we tested effects of periadventitial delivery of resveratrol on all three major pro-restenotic pathologies including intimal hyperplasia (IH), endothelium impairment, and vessel shrinkage. In a rat carotid injury model, periadventitial delivery of resveratrol either via Pluronic gel (2-week), or polymer sheath (3-month), effectively reduced IH without causing endothelium impairment and vessel shrinkage. In an in vitro model, primary smooth muscle cells (SMCs) were stimulated with elevated transforming growth factor (TGFß) and its signaling protein Smad3, known contributors to IH. TGFß/Smad3 up-regulated Kruppel-like factor (KLF5) protein, and SMC de-differentiation which was reversed by KLF5 siRNA. Furthermore, TGFß/Smad3-stimulated KLF5 production and SMC de-differentiation were blocked by resveratrol via its inhibition of the Akt-mTOR pathway. Concordantly, resveratrol attenuated Akt phosphorylation in injured arteries. Taken together, periadventitial delivery of resveratrol produces durable inhibition of all three pro-restenotic pathologies - a rare feat among existing anti-restenotic methods. Our study suggests a potential anti-restenotic modality of resveratrol application suitable for open surgery.

A "cluster" based search scheme in peer-to-peer network.

This paper presents a "cluster" based search scheme in peer-to-peer network. The idea is based on the fact that data distribution in an information society has structured feature. We designed an algorithm to cluster peers that have similar interests. When receiving a query request, a peer will preferentially forward it to another peer which belongs to the same cluster and shares more similar interests. By this way search efficiency will be remarkably improved and at the same time good resilience against peer failure (the ability to withstand peer failure) is reserved.

Halofuginone stimulates adaptive remodeling and preserves re-endothelialization in balloon-injured rat carotid arteries.

BACKGROUND: Three major processes, constrictive vessel remodeling, intimal hyperplasia (IH), and retarded re-endothelialization, contribute to restenosis after vascular reconstructions. Clinically used drugs inhibit IH but delay re-endothelialization and also cause constrictive remodeling. Here we have examined halofuginone, an herbal derivative, for its beneficial effects on vessel remodeling and differential inhibition of IH versus re-endothelialization. METHODS AND RESULTS: Two weeks after perivascular application to balloon-injured rat common carotid arteries, halofuginone versus vehicle (n=6 animals) enlarged luminal area 2.14-fold by increasing vessel size (adaptive remodeling; 123%), reducing IH (74.3%) without inhibiting re-endothelialization. Consistent with its positive effect on vessel expansion, halofuginone reduced collagen type 1 (but not type 3) production in injured arteries as well as that from adventitial fibroblasts in vitro. In support of its differential effects on IH versus re-endothelialization, halofuginone produced greater inhibition of vascular smooth muscle cell versus endothelial cell proliferation at concentrations ≈50 nmol/L. Furthermore, halofuginone at 50 nmol/L effectively blocked Smad3 phosphorylation in smooth muscle cells, which is known to promote smooth muscle cell proliferation, migration, and IH, but halofuginone had no effect on phospho-Smad3 in endothelial cells. CONCLUSIONS: Periadventitial delivery of halofuginone dramatically increased lumen patency via adaptive remodeling and selective inhibition of IH without affecting endothelium recovery. Halofuginone is the first reported small molecule that has favorable effects on all 3 major processes involved in restenosis.

Perfusing chemotherapy by percutaneous lung puncture "holing" for pulmonary tuberculoma-a ten-year single center experience.

BACKGROUND: Pulmonary tuberculoma is a special form of secondary pulmonary tuberculosis, with a poor response to drug treatment. We used the method of drug administration via percutaneous lung puncture "holing" to treat pulmonary tuberculoma and observe its short- and long-term efficacy, summing up our 10-year clinical experience. METHODS: A total of 54 patients with pulmonary tuberculoma were included in this study. They themselves were taken as the control group. Three to six months of conventional anti-tuberculosis treatment was conducted firstly. Then those patients with no changes of sizes in tuberculoma were recommended to receive drug administration via percutaneous lung puncture. Isoniazid (INH, 0.1 g) and amikacin (AMK, 0.2 g) were injected into tuberculoma (once or twice per week, 10 times as a course of treatment). RESULTS: After two months of drug treatment by lung puncture, the sputum smear test showed the negative conversion rate of tubercle bacillus was 87% (13/15), and the positive conversion rate was 8% (3/39). The tuberculosis bacillus culture indicated that the negative conversion rate was 100% (7/7). The reexamination after one year showed the negative conversion rate of tubercle bacillus in the sputum smear test was 80% (4/5). About 58% (31/54) of tuberculoma disappeared or significantly reduced, in which, 40% (21/54) of tuberculoma disappeared. The tuberculoma diameter reduced from 3.6 cm × 2.8 cm to 1.7 cm × 1.1 cm on average. Side-effects included postoperative pneumothorax 9% (5/54), hemoptysis 7% (4/54) and fever 11% (6/54). A total of 34 patients were followed up for five years, and the disappearance rate of tuberculoma was up to 47% (16/34), with no recurrence. CONCLUSIONS: The drug administration via percutaneous lung puncture-"holing" in pulmonary tuberculoma takes a significant effect obviously, good short- and long-term effects and less side effects.

Preferential secretion of collagen type 3 versus type 1 from adventitial fibroblasts stimulated by TGF-ß/Smad3-treated medial smooth muscle cells.

Restenosis, or arterial lumen re-narrowing, occurs in 30-50% of the patients undergoing angioplasty. Adaptive remodeling is the compensatory enlargement of the vessel size, and has been reported to prevent the deleterious effects of restenosis. Our previous studies have shown that elevated transforming growth factor (TGF-ß) and its signaling protein Smad3 in the media layer induce adaptive remodeling of angioplastied rat carotid artery accompanying an increase of total collagen in the adventitia. In order to gain insights into a possible role of collagen in Smad3-induced adaptive remodeling, here we have investigated a mechanism of cell-cell communication between medial smooth muscle cells (SMCs) and adventitial fibroblasts in regulating the secretion of two major collagen subtypes. We have identified a preferential collagen-3 versus collagen-1 secretion by adventitial fibroblasts following stimulation by the conditioned medium from the TGF-ß1-treated/Smad3-expressing medial smooth muscle cells (SMCs), which contained higher levels of CTGF and IGF2 as compared to control medium. Treating the TGF-ß/Smad3-stimulated SMCs with an siRNA to either CTGF or IGF2 reversed the effect of conditioned media on preferential collagen-3 secretion from fibroblasts. Moreover, recombinant CTGF and IGF2 together stimulated adventitial fibroblasts to preferentially secrete collagen-3 versus collagen-1. This is the first study to identify a preferential secretion of collagen-3 versus collagen-1 from adventitial fibroblasts as a result of TGF-ß/Smad3 stimulation of medial SMCs, and that CTGF and IGF2 function together to mediate this signaling communication between the two cell types.