Apoptosis involves phospholipid components of the cell membrane. The event modifies the metabolism of phos- phatidylserine (PS), which is exposed to the exterior. It also involves PLA2s, which represent the limiting step for powerful lipid mediators synthesis. GBS has developed several strategies to evade immune defences, particularly GBS induces macrophage apoptosis by cal- cium influx and calpain activation which are inhibited by EGTA (Fettucciari et al., 2006). To evaluate the role of PLA2s we measured [3H]arachidonic acid (AA) release from macrophage phospholipids. GBS infec- tion increased [3H]AA release both in macrophages and in the medium, demonstrating PLA2s activation. EGTA did not modify the extent of [3H]AA release in macrophages, but significantly decreased the release in the medium. These results suggest a contribution of dif- ferent PLA2s in the production of AA from membrane phospholipids. We also investigated on the mechanism by which GBS-induced apoptosis reduces PS radioactiv- ity of macrophages incubated with [3H]serine (Buratta et al., 2002). The reduction of PS radioactivity was not modified by the presence of EGTA in the medium and may involve a particular isoform of PS synthesising enzyme. Acknowledgement: Grant from Fondazione Cassa di Risparmio di Perugia (2005). References Fettucciari, K., et al. 2006. J. Immunol. 176, 7542. Buratta, S., et al., 2002. FEBS Lett. 520, 68.
Group B streptococcus (GBS) causes macrophage PLA2s activation and modification of phosphatidyl- serine metabolism during induction of apoptosis
BURATTA, Sandra;FETTUCCIARI, Katia;NARDICCHI, Vincenza;FETRICONI, ILARIA;FELICETTI, MICHELA;MACCHIONI, Lara;MOZZI, Rita;MARCONI, Pierfrancesco;GORACCI, Gianfrancesco
2006
Abstract
Apoptosis involves phospholipid components of the cell membrane. The event modifies the metabolism of phos- phatidylserine (PS), which is exposed to the exterior. It also involves PLA2s, which represent the limiting step for powerful lipid mediators synthesis. GBS has developed several strategies to evade immune defences, particularly GBS induces macrophage apoptosis by cal- cium influx and calpain activation which are inhibited by EGTA (Fettucciari et al., 2006). To evaluate the role of PLA2s we measured [3H]arachidonic acid (AA) release from macrophage phospholipids. GBS infec- tion increased [3H]AA release both in macrophages and in the medium, demonstrating PLA2s activation. EGTA did not modify the extent of [3H]AA release in macrophages, but significantly decreased the release in the medium. These results suggest a contribution of dif- ferent PLA2s in the production of AA from membrane phospholipids. We also investigated on the mechanism by which GBS-induced apoptosis reduces PS radioactiv- ity of macrophages incubated with [3H]serine (Buratta et al., 2002). The reduction of PS radioactivity was not modified by the presence of EGTA in the medium and may involve a particular isoform of PS synthesising enzyme. Acknowledgement: Grant from Fondazione Cassa di Risparmio di Perugia (2005). References Fettucciari, K., et al. 2006. J. Immunol. 176, 7542. Buratta, S., et al., 2002. FEBS Lett. 520, 68.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
