Increased oxygen radical and eicosanoid formation in immune-mediated mesangial cell injury

Increased oxygen radical and eicosanoid formation in immune-mediated mesangial cell injury. To evaluate whether monocytes/macrophages derived from glomeruli could be a source of increased eicosanoid and free oxygen radical formation in glomerular disease, monocytes/macrophage (M/M) were isolated from nephritic glomeruli and their in vitro generation of eicosanoids and superoxides were measured. Glomerular immune injury was induced by i.v. injection of a rabbit-anti-rat thymocyte antiserum (ATS). Kidneys were removed two, five, and 24 hours, and three and eight days after ATS. Adhesive glomerular macrophages were obtained by isolation of glomeruli, enzymatic digestion and incubation of the single cell suspensions in culture dishes. O2-production was evaluated by superoxide dismutase (SOD)-inhibitable reduction of ferricytochrome C; PGE2 and TxB2 release was assessed by direct RIA. Glomerular macrophage infiltration was maximal 24 hours after intravenous antibody (35.9 ± 5.1 M/M per glomerulus). In vitro production of superoxide was significantly enhanced (P < 0.001) five hours after ATS administration (51.6 ± 4.4nmol O2/106 MM/hr), when compared with M/M from controls (30.4 ± 2.0nmol O2/106 MM/hr). TxB2 formation of glomerular M/M was increased (P < 0.001) two hours and five hours after ATS administration (1056 ± 75 and 1182 ± 112pg TxB2/106 MM/hr) compared with controls (390 ± 34pg TxB2/106 MM/hr). PGE2 synthesis, however, was decreased (P < 0.01) at five hours after ATS (629 ± 43pg PGE2/106 MM/hr) compared with controls (950 ± 125pg PGE2/106 MM/hr). Furthermore, there was release of leukotriene B4 (LTB4) in monocytes of nephritic glomeruli five hours after ATS administration. These data demonstrate that monocytes/macrophages from nephritic glomeruli release increased amounts of superoxide and thromboxane B2, whereas prostaglandin E2 synthesis is decreased. These alterations might contribute to the hemodynamic and structural lesions in this model of glomerular injury