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Increased oxygen radical and eicosanoid formation in immune-mediated mesangial cell injury
G P Oberle1, J Niemeyer, F Thaiss
1Department of Medicine, University of Frankfurt a.M., Germany.
Abstract:
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 less than 0.001) five hours after ATS administration (51.6 +/- 4.4 nmol O2/10(6) MM/hr), when compared with M/M from controls (30.4 +/- 2.0 nmol O2/10(6) MM/hr). TxB2 formation of glomerular M/M was increased (P less than 0.001) two hours and five hours after ATS administration (1056 +/- 75 and 1182 +/- 112 pg TxB2/10(6) MM/hr) compared with controls (390 +/- 34 pg TxB2/10(6) MM/hr). PGE2 synthesis, however, was decreased (P less than 0.01) at five hours after ATS (629 +/- 43 pg PGE2/10(6) MM/hr) compared with controls (950 +/- 125 pg PGE2/10(6) MM/hr). Furthermore, there was release of leukotriene B4 (LTB4) in monocytes of nephritic glomeruli five hours after ATS administration.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Monocytes/macrophages in diseased glomeruli significantly increase superoxide and thromboxane B2 (TxB2) production, while decreasing prostaglandin E2 (PGE2) synthesis. This suggests these cells contribute to glomerular injury via inflammatory mediators.
Area of Science:
- Nephrology
- Immunology
- Cell Biology
Background:
- Glomerular disease involves inflammatory processes.
- Monocytes/macrophages are key immune cells implicated in kidney injury.
Purpose of the Study:
- To investigate if glomerular monocytes/macrophages contribute to eicosanoid and free oxygen radical formation in glomerular disease.
- To quantify superoxide, PGE2, and TxB2 production by isolated glomerular macrophages.
Main Methods:
- Glomerular immune injury induced using rabbit-anti-rat thymocyte antiserum (ATS).
- Isolation of adhesive glomerular macrophages via enzymatic digestion.
- Measurement of superoxide production using ferricytochrome C reduction.
- Quantification of PGE2 and TxB2 by radioimmunoassay (RIA).
Main Results:
- Macrophage infiltration peaked 24 hours post-ATS.
- Superoxide production by glomerular macrophages significantly increased 5 hours post-ATS (P < 0.001).
- Thromboxane B2 (TxB2) formation increased significantly at 2 and 5 hours post-ATS (P < 0.001).
- Prostaglandin E2 (PGE2) synthesis decreased significantly at 5 hours post-ATS (P < 0.01).
- Leukotriene B4 (LTB4) was released by monocytes 5 hours post-ATS.
Conclusions:
- Glomerular monocytes/macrophages are a source of enhanced superoxide and TxB2 production during immune-mediated glomerular injury.
- The altered eicosanoid profile (decreased PGE2, increased TxB2) suggests a pro-inflammatory role for these cells.
- These findings highlight the contribution of glomerular macrophages to the pathogenesis of glomerular disease.