Until recently, models of microglial activation were based on macrophage activation, which was often simplified to classical activation, evoked by exposure to interferon or bacterial toxins, inhibitor Pazopanib and alternative activation, which is evoked by interleukin 4 or IL13. Based on in vitro studies of microglia, it is clear that LPS can upregulate Inhibitors,Modulators,Libraries pro inflammatory cytokines, excitatory amino acids, proteases, and reactive oxygen and nitrogen species. Ex posure to LPS can inhibit neurogenesis and exert neurotoxic effects in vitro and in vivo. Conversely, alternative activation, often characterized by increases in hallmark genes such as arginase 1 and the mannose receptor C type 1, is thought to help resolve acute inflammation by antagoni zing pro inflammatory mediators, initiating repair and reconstructing the ECM.

Both IL4 stimulated macro phages and microglia generally produce less nitric oxide and more Inhibitors,Modulators,Libraries L proline and type 2 cytokines that help promote tissue repair. There is evidence that IL4 treated microglia promote neuroprotection, neurogen esis and oligodendrocyte genesis. It is increasingly Inhibitors,Modulators,Libraries recognized that responses of microglia to CNS injury are more complex than M1 and M2 macrophage activation, and are likely modulated Inhibitors,Modulators,Libraries by the type of injury, timing and environment, possibly involving a continuum of states. Here, as in numerous papers, to model the two ex tremes of microglial activation in vitro, we use LPS to induce classical activation and IL4 to induce alternative activation. The purpose of this study was to analyze how these activation states affect microglial migration, inva sion, and the enzymes used for ECM degradation in vitro.

We compared morphological Inhibitors,Modulators,Libraries hallmarks of mi grating cells axis and quantified random migration, chemotaxis in response to adenosine triphosphate, and invasion through Matrigel. Finally, we compared microglial expression of nine matrix degrading enzymes in three classes, and ca thepsins and used a panel of inhibitors to address their contributions to invasion. Because microglia migrate in vivo after many types of damage and disease, we ini tially expected that they would migrate and invade well, regardless of their activation state. Instead, our results show that microglial morphology, migration, invasion, and matrix degrading enzyme usage differed depending on the activation state.

Materials and methods Cell cultures All procedures on animals were approved by the Univer sity Health Network Animal Care Committee, in accord ance with guidelines from the Canadian Council on Animal our website Care. Our standard protocols were used to isolate and culture primary microglia from 1 to 2 day old Sprague Dawley rat pups. Most importantly, these methods produce 99% pure microglia, and greatly re duce their levels of spontaneous activation.