Blockade of Smooth Muscle Cell Migration and Proliferation in Baboon Aortic Explants by Interleukin-1β and Tumor Necrosis Factor-α Is Nitric Oxide-Dependent and Nitric Oxide-Independent

Abstract

Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNFα) are found in injured and atherosclerotic vessels and have been shown to influence smooth muscle cell (SMC) function in vitro. We have investigated the effects of IL-1β and TNFα on SMC migration and proliferation in baboon aortic explants, an in vitro model of arterial injury. Because platelet-derived growth factor (PDGF) is also present in the vessel wall, we have studied the interaction of PDGF with the cytokines. IL-1β and TNFα inhibited migration of SMCs and synthesis of DNA by SMCs. Cell death (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells and total DNA) was not altered by the cytokines. The cytokines increased levels of nitrite in the medium and L-nitroarginine partly reversed the inhibitory effects of the cytokines indicating a role for nitric oxide in these inhibitory effects. Treatment with indomethacin partially reversed the inhibition of migration, but not DNA synthesis by IL-1β suggesting cyclooxygenase products play an inhibitory role in migration. PDGF-BB reversed the inhibitory effect of the cytokines on SMC migration, but not mitogenesis, without changing levels of nitrite in the medium. These data show that IL-1β and TNFα decrease primate SMC migration and proliferation in arterial tissue partly through production of NO, and that PDGF antagonizes the effect of the cytokines. IL-1β and TNFα may act directly to limit injury-induced intimal hyperplasia by decreasing SMC migration and proliferation.

Cell Death–associated ADAMTS4 and Versican Degradation in Vascular Tissue

“…The amount of medium loaded per lane is 5% of the total, and the tissue extract loaded is 20%. Asterisk: ADAMTS4 bands remaining from previous blot of membrane in A. explants (Kenagy and Clowes 2000), these results are consistent with an association between cell death and synthesis of ADAMTS4. Therefore, to determine whether death induces ADAMTS4 expression, we tested the effect of FasL on ADAMTS4 mRNA levels.…”

“…Scoring of staining intensity as higher, lower, or the same between the paired high-and normal-flow grafts was performed blinded. For double labeling for ADAMTS4 and cell death, sections were first stained with antibody to ADAMTS4 as previously described (Kenagy et al 2005), followed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) as previously described (Kenagy and Clowes 2000). Images were acquired using a DP70 CCD color camera (RGB, 12 bits/channel; Olympus America, Inc.; Center Valley, PA) using DP70 controller/manager software v3.02 with one-touch color balancing.…”

TNF-α induces proliferation or apoptosis in human saphenous vein smooth muscle cells depending on phenotype

“…Therefore, it seems possible that the effect of ANG II would depend on the predominance of the phenotype in the experimental situation. Furthermore, as described in the opening of this report, previous investigations using primary VSMC cultures have shown conflicting effects of TNF (11,12,15,19,22,28,32,38,39,53). Here we addressed the question of whether the diversity in the biological effects of TNF could originate from variations in the different VSMC subtypes.…”

“…The combination of TNF with its receptors induces multiple signals that result in effects on cells that are dependent on cell type. In studies of the activity of TNF on VSMCs, this cytokine has been consistently shown to be a chemoattractant; however, the effects on proliferation of VSMCs are conflicting (11,12,15,19,21,22,28,32,38,39,49,53). Several investigations reported that TNF itself had no effect on VSMC proliferation (19,28).…”

“…Similarly, investigations on the induction of apoptosis or the inhibition of proliferation by TNF are not consistent. Some investigators found no proapoptotic activity for TNF, whereas others found that under certain conditions, TNF was proapoptotic and activated apoptosis-related caspase-3 (11,12,15,22,32,53). Thus it seems possible that TNF can induce both proliferation and apoptosis in VSMCs and regulate vascular intimal cellularity by a balance of these two effects.…”