A selective inhibitor of p38 MAP kinase, SB202190, induced apoptotic cell death of a lipopolysaccharide-treated macrophage-like cell line, J774.1

A selective p38 MAP kinase (p38 MAPK) inhibitor, SB202190, induced apoptoti c cell death of a macrophagelike cell line, J774.1, in the presence of lipo polysaccharide (LPS), as judged by DNA nicks revealed by terminal deoxy tra nsferase (TdT)-mediated dUTP nick end labeling (TUNEL), activation of caspa se-3, and subsequent release of lactate dehydrogenase. This cytotoxicity wa s dependent on both LPS and SB202190, and such inhibitors of the upstream L PS-signaling cascade as polymyxin B and TPCK blocked this macrophage cell d eath. SB202190 suppressed the kinase activity of p38, leading to inhibition of activation of MAPKAPK2 and then the subsequent phosphorylation of hsp27 in LPS-treated macrophages both in vitro and in vivo, but an inactive anal og of SB202190, SB202474, did not. There was a threshold of the time of add ition of SB202190 to LPS-treated macrophages to induce apoptosis, which was before full transmission of p38 activity to a direct downstream kinase, MA PKAPK2. Besides, localization of phosphorylated hsp27 in Golgi area of the LPS-treated macrophages was suppressed by SB202190, while it was not by SB2 02474. These results suggest that selective inhibition of p38 MAPK activity in LPS-induced MAP kinase cascade leads to apoptosis of macrophages. (C) 2 000 Elsevier Science B.V. All rights reserved.