Chloroquine-induced neuronal cell death is p53 and Bcl-2 family-dependent but caspase-independent.

Chloroquine is a lysosomotropic agent that causes marked changes in intracellular protein processing and trafficking and extensive autophagic vacuole formation. Chloroquine may be cytotoxic and has been used as a model of lysosomal-dependent cell death. Recent studies indicate that autophagic cell death may involve Bcl-2 family members and share some features with caspase-dependent apoptotic death. To determine the molecular pathway of chloroquine-induced neuronal cell death, we examined the effects of chloroquine on primary telencephalic neuronal cultures derived from mice with targeted gene disruptions in p53, and various caspase and bcl-2 family members. In wild-type neurons, chloroquine produced concentration- and time-dependent accumulation of autophagosomes, caspase-3 activation, and cell death. Cell death was inhibited by 3-methyladenine, an inhibitor of autophagic vacuole formation, but not by Boc-Asp-FMK (BAF), a broad caspase inhibitor. Targeted gene disruptions of p53 and bax inhibited and bcl-x potentiated chloroquine-induced neuron death. Caspase-9- and caspase-3-deficient neurons were not protected from chloroquine cytotoxicity. These studies indicate that chloroquine activates a regulated cell death pathway that partially overlaps with the apoptotic cascade.

Spontaneous and continuous cyclooxygenase-2-dependent prostaglandin E2 production by stromal cells in the murine small intestine lamina propria: directing the tone of the intestinal immune response.

The mechanisms allowing the gastrointestinal immune system to avoid an inappropriate inflammatory response to nonpathogenic luminal Ags are poorly understood. We have previously described a role for cyclooxygenase (COX)-2-dependent arachidonic acid metabolites produced by the murine small intestine lamina propria in controlling the immune response to a dietary Ag. To better understand the role of COX-2-dependent arachidonic acid metabolites produced by the lamina propria, we examined the pattern of expression and the cellular source of COX-2 and COX-2-dependent PGE(2). We now demonstrate that non-bone marrow-derived lamina propria stromal cells have basal COX-2 expression and that COX-2-dependent PGE(2) production by these cells is spontaneous and continuous. The other mucosal and nonmucosal lymphoid compartments examined do not share this phenotype. In contrast to the majority of descriptions of COX-2 expression, COX-2 expression by lamina propria stromal cells is not dependent upon exogenous stimuli, including adhesion, LPS signaling via Toll-like receptor 4, or the proinflammatory cytokines TNF-alpha, IFN-gamma, and IL-1 beta. These findings, in conjunction with the known immunomodulatory capacities of PGs, suggest that COX-2 expression by the small intestine lamina propria is a basal state contributing to the hyporesponsiveness of the intestinal immune response.