PAI 1 mRNA levels were also augmented by inflammatory stimulation in microglia and astrocytes. LPS, alone or in combination with IFN, enhanced PAI 1 mRNA expres sion to varying degrees in glial cell lines and cultures, but IFN alone did not have a significant effect. These results cell assay indicate that both microglia and astro cytes can be the major cellular sources of PAI 1 in the CNS under inflammatory conditions. Plasminogen activator inhibitor type 1 promotes microglial migration, but not microglial proliferation or neurotoxic activation Having shown that both microglia and astrocytes secrete PAI 1 upon inflammatory stimulation, we next sought to determine how glia derived PAI 1 influences proinflam matory phenotypes of microglia.
We focused on microglial migration, nitric oxide production, and neurotoxicity, because it has been suggested that activated microglia are recruited Inhibitors,Modulators,Libraries to inflammatory sites and produce NO and other proinflammatory mediators, amplifying neuroinflammation and exerting neurotoxic effects. Effects of PAI 1 on microglial cell migration were first investigated Inhibitors,Modulators,Libraries using an in vitro wound Inhibitors,Modulators,Libraries healing assay and Boyden chamber assay. The mean plasma concentration of PAI 1 under physiological conditions is about 6 to 80 ng ml, but it can be increased in a number of pathological conditions. In the migra tion assay, we used 1 to 1000 ng ml of recombinant mouse PAI 1 protein, which is equivalent to 0. 022 to 22. 0 nmol l. We found that PAI 1 promoted migration of BV 2 microglial cells in a dose dependent manner.
Significant effects on microglial migration were seen after treatment with 10 ng ml or higher concentrations of PAI 1 protein. Effects of BSA Inhibitors,Modulators,Libraries at the same molar concen tration were compared as a con trol. Sensitivity of microglia to PAI 1 was similar to that of rat and human smooth muscle cells, MEF 1 fibroblasts, and HT1080 fibrosarcoma cells. PAI 1 did not affect microglial proliferation, indicating Inhibitors,Modulators,Libraries that the PAI 1 promotion of wound recovery was not related to microglial cell proliferation. PAI 1 also increased migration of primary microglia cultures. These results, taken collectively, indicate that PAI 1 promotes the migration of microglia in cul ture. PAI 1 also increased C6 rat glioma cell migration by about 1. 25 fold over control, suggesting that PAI 1 may exert similar effects on the dynamics of microglia and astrocytes.
However, the effects of PAI 1 on astrocytes were not further investigated in this study. Next, we determined whether PAI 1 could directly affect microglial activation. Because activated microglia release NO and other neurotoxic mediators, microglial NO selleck chem Olaparib pro duction and neurotoxicity was measured to assess micro glial activation. The recombinant mouse PAI 1 protein did not affect LPS induced NO production or cell viability in BV 2 microglial cells or primary microglia cultures. PAI 1 did not influence microglial neurotoxicity in microglia neuron cocultures.
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