Selective inhibition of protein kinase C, mitogen-activated protein kinase, and neutrophil activation in response to calcium pyrophosphate dihydrate crystals, formyl-methionyl-leucyl-phenylalanine, and phorbol ester by O-(chloroacetyl-carbamoyl) fumagillol (AGM-1470; TNP-470)

The effect of O-(chloroacetyl-carbamoyl) fumagillol (AGM-1470; TNP-470) was investigated on protein kinase C (PKC) and mitogen-activated protein kinas e (MAPK) activation in neutrophils stimulated by plasma-opsonized crystals of calcium pyrophosphate dihydrate (triclinic) [CPPD(T)], formyl-Met-Leu-Ph e (fMLP), and phorbol 12-myristate 13-acetate (PMA). Neutrophil respiratory burst responses also were determined in AGM-1470-pretreated cells stimulat ed with the same agonists, using chemiluminescence and superoxide anion gen eration assays. AGM-1470 (5 mu M) effectively inhibited PKC activation in c ells treated with CPPD(T) crystals (50 mg/mL, 2 min) and fMLP (1 mu M, 1 mi n), but had no effect on PMA-treated cells (0.5 mu M, 5 min). AGM-1470 bloc ked MAPK activity completely and reduced neutrophil activation induced by f MLP and PMA but not by CPPD(T). The degree of inhibition of the respiratory burst plateaued at approximately 46 +/- 9 and 54 +/- 3% in fMLP- and PMA-t reated cells, respectively. These data indicate that. activation of neutrop hil respiratory burst activity may be mediated through the MAPK pathway. AG M-1470 pretreatment did not inhibit CPPD(T) crystal- or fMLP-stimulated pho sphatidylinositol 3-kinase (PI 3-kinase) activity. These findings, coupled with further observations that the PI 3-kinase inhibitor wortmannin (10 nM) inhibited fMLP- and CPPD(T) crystal-induced but not PMA-induced chemilumin escence, indicate that at least two distinct signaling pathways (mediated b y PI 3-kinase or MAPK) lead to neutrophil respiratory burst responses. PKC may also be required in the MAPK-stimulated pathway. We propose that the in hibitory effect of AGM-1470 on the neutrophil respiratory burst may be due to its ability to inhibit PKC and MAPK activation. (C) 1999 Elsevier Scienc e Inc.