The anti-inflammatory drug CNI-1493 regulates the intracellular processing of Aβ in different cell types of the brain

Recently, we have reported that the potent anti-inflammatory p38-MAPK-inhibitor CNI-1493 is capable to decrease the extracellular Aβ production in vitro (Bacher et al., J Exp Med. 2008). This phenomenon-was also confirmed by our in vivo experiment showing that the soluble Aβ fraction was markedly reduced in an APP transgenic mouse model following CNI-1493 administration. One possible explanation for the CNI-1493 dependent decrease of extracellular Aβ in cell culture supernatants or within the brain cytosol fraction is now being offered by our present study which showed a profound uptake of soluble Aβ species following coincubation with CNI-.1493. Of note, this CNI-1493 dependent uptake of Aβ occurred in a neuronal as well as in a microglial cell line. This data may suggest that the cellular Aβ uptake mechanism induced by CNI-1493 is similar in both cell types of the brain. Interestingly, the intracellular increase in Aβ was not accompanied by an extended dysfunction or cell death in both cell lines. Additionally, we could demonstrate that CNI-1493 reduced the Aβ mediated proinflammatoty cytokine release of TNF-α and IL-6 of the microglial cell line BV-2. We further investigated whether CNI-1493 stimulates Aβ species uptake by increasing unspecific pinocytosis or if it has an influence on specific receptor mediated internalisation of Aβ species. Therefore we used DMA (Dimethylamiloride hydrochloride) to examine whether CNI-1493 may influence pinocytosis of Aβ in both described cell lines. Furthermore, we tested Dynasore, a potent inhibitor of endocytosis to elucidate how Aβ is internalized into our investigated cell lines. As the α-7 nicotinic Acetlycholine receptor has been suggested to participate in Aβ-uptake (Nagele et al., Neuroscience 2002) we also treated BV-2 and N2a cells with α-BTX in an attempt to block internalisation.