Real-time monitoring of mesangial cell-macrophage cross-talk using SEAP in vitro and ex vivo.

BACKGROUND: Macrophage-mesangial cell interaction plays a crucial role in the pathogenesis of glomerulonephritis. We established a novel system for continuous, real-time monitoring of cross-talk between macrophages and mesangial cells in vitro and ex vivo.
METHODS: Rat mesangial cells were genetically engineered to produce secreted alkaline phosphatase (SEAP) under the control of the nuclear factor-kappaB (NF-kappaB) enhancer elements. The established sensor cells were exposed to macrophages or macrophage-derived factors, and the level of SEAP production was evaluated.
RESULTS: In vitro, the established cells expressed and secreted SEAP when exposed to activated macrophages or to cytokines produced by macrophages. The kinetics of SEAP activity in culture media was closely correlated with the expression level of SEAP mRNA. The sensor cells also secreted SEAP in response to media conditioned by macrophage-accumulating, inflamed rat glomeruli. When the sensor cells were transferred adoptively into rat glomeruli subjected to acute anti-Thy 1 glomerulonephritis, the isolated glomeruli containing sensor cells secreted SEAP rapidly and progressively.
CONCLUSION: These data suggested that the established system provides simple and useful tools for monitoring of cross-talk between macrophages and mesangial cells in vitro and ex vivo. This approach would be useful for investigation of molecular mechanisms involved in mesangial cell-macrophage interaction and also for screening of therapeutic agents that efficiently interfere with the link between infiltrating leukocytes and resident glomerular cells.