RESUMO
We examined the effect of PGE1 on the expression of plasminogen activator inhibitor-1 (PAI-1) mRNA induced by tumor necrosis factor-alpha (TNF-alpha) in human mesangial cells, because PAI-1 is one of major factors for the progression of glomerulosclerosis. The expression of PAI-1 mRNA was increased after stimulation with TNF-alpha, and it was diminished by pre-incubation with PGE1. Next, we examined the effect of PGE1 on the phosphorylation of mitogen activated protein kinase (MAPK) family and Akt. TNF-alpha activated the phosphorylation of p44/42 MAPK, p38 MAPK, SAPK/JNK and Akt in mesangial cells. PGE1 inhibited the TNF-alpha induced phosphorylation of SAPK/JNK and Akt, but not p44/42 MAPK and p38 MAPK. The TNF-alpha induced expression of PAI-1 mRNA was not affected by PD98059, an inhibitor of MEK, SB203580, an inhibitor of p38 MAPK, nor LY294002, an inhibitor of PI3 K. However, DMAP, an inhibitor of SAPK/JNK, inhibited the expression of PAI-1 mRNA, suggesting that the TNF-alpha induced expression of PAI-1 mRNA is regulated by the SAPK/JNK dependent pathway in human mesangial cells. By the incubation with H8, an inhibitor of PKA, the inhibitory effect of PGE1 on the expression of PAI-1 mRNA was abolished, suggesting that PGE1 inhibited the PAI-1 mRNA expression via the PKA pathway. Our results suggest that the inhibition of PAI-1 synthesis by PGE1 in human mesangial cells may have therapeutic implications for glomerulosclerosis such as occurs in diabetic nephropathy.
Assuntos
Alprostadil/farmacologia , Nefropatias Diabéticas/imunologia , Mesângio Glomerular/efeitos dos fármacos , Inibidor 1 de Ativador de Plasminogênio/biossíntese , Fator de Necrose Tumoral alfa/farmacologia , Northern Blotting , Western Blotting , AMP Cíclico/metabolismo , Interações Medicamentosas , Mesângio Glomerular/metabolismo , Humanos , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , Inibidor 1 de Ativador de Plasminogênio/genética , Inibidores de Proteínas Quinases/farmacologia , Fator de Necrose Tumoral alfa/antagonistas & inibidoresRESUMO
It has been reported that alpha-tocopherol, an antioxidant agent, may play a role in preventing diabetic angiopathy. However, there is little evidence to show the effect of alpha-tocopherol on the production of pro-inflammatory cytokines in endothelial cells. Therefore, we examined the effect of alpha-tocopherol on the regulation of IL-8 synthesis induced by high glucose and/or thrombin in endothelial cells. Thrombin alone markedly increased the IL-8 release. Furthermore, high glucose levels and thrombin combined had additive effects on IL-8 synthesis, and alpha-tocopherol diminished their effect; alpha-tocopherol also inhibited the phosphorylation of IkappaB-alpha induced by high glucose levels and/or thrombin. Our results suggest that the administration of alpha-tocopherol to diabetic patients may have a beneficial effect for the prevention of diabetic vascular complications by the inhibition of IL-8 synthesis from endothelial cells.
Assuntos
Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Glucose/farmacologia , Proteínas I-kappa B , Interleucina-8/biossíntese , Trombina/farmacologia , alfa-Tocoferol/farmacologia , Aorta , Células Cultivadas , Proteínas de Ligação a DNA/metabolismo , Interações Medicamentosas , Glucose/administração & dosagem , Humanos , Interleucina-8/genética , Inibidor de NF-kappaB alfa , Fosforilação , RNA Mensageiro/análise , Transdução de SinaisRESUMO
1. 3-Hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors (statins) prevent the progression of atherosclerosis by lowering cholesterol. However, the effect of statins on the synthesis of pro-inflammatory cytokines from endothelial cells has not yet been fully investigated. Here, we examined the effect of pravastatin, one of the statins, on IL-8 synthesis induced by thrombin in human aortic endothelial cells (AoEC) cultured with high glucose concentrations. 2. Pravastatin significantly decreased the IL-8 synthesis induced by thrombin. 3. Pravastatin inhibited the p44/42 MAP kinase activity induced by thrombin, but did not inhibit the p38 MAP kinase activity. 4. Translocation of ras protein from the cytosol to plasma membrane was inhibited by pravastatin. 5. Pravastatin inhibit the activator protein-1 activity, but did not inhibit the activation of IkappaB-alpha. 6. Dominant negative ras inhibited the p44/42 MAP kinase activity induced by PMA. 7. Our results suggest that pravastatin inhibits IL-8 synthesis by blocking the ras-MAP (p44/42) kinase pathway rather than nuclear factor-kappaB. Pravastatin may prevent atherosclerosis not only by lowering cholesterol levels, but also by suppressing IL-8 synthesis in AoEC through the inhibition of p44/42 MAP kinase, and this may be more beneficial in diabetic patients than in non-diabetics.
