Regulation of microglial response. Expression kinetics of genes, involved in microglia regulation, in response to pneumococcal infection. A) Components of the Toll-like receptor pathway initiating the innate immune response, pro-inflammatory mediators and microglial "On" signals show their expression maxima in the acute phase of the disease at 1 day post infection (hpi). B) At 3 days after infection we find an expressional peak of transcripts coding for receptors that guide the resting microglia to the site of action and which orchestrate phagocytic and trophic functions during tissue regeneration. Furthermore there is a transcriptional peak of factors expressed in activated microglia which lead to a down-modulation of the immune response.