Antiserum against tumor necrosis factor-alpha and a protease inhibitor reduce immune glomerular injury.

Previous studies in this laboratory have documented tumor necrosis factor alpha (TNF) release by macrophage laden glomeruli in the accelerated autologous form of nephrotoxic serum nephritis (AA-NTSN). We now report that the administration of anti-TNF antiserum to rats with the AA-NTSN reduces albuminuria in a dose related manner (day 8 postinduction) and limits glomerular necrosis (P less than 0.05) without affecting the endogenous creatinine clearance (CCr). Protease inhibitors block cytolytic activity of TNF in vitro and reduce glomerular necrosis in experimental nephritis in vivo. The combined administration of anti-TNF antiserum and an amidine-type protease inhibitor (BABIM) to rats with the AA-NTSN caused a greater diminution of albuminuria and histopathology than observed in rats treated with either agent alone, and also prevented the fall in CCr otherwise observed in this model system. Since, in our studies, BABIM did not inhibit cytolytic TNF activity in vitro, we conclude that the effects of combined administration of these two agents are mediated by independent mechanisms. Our results highlight the pathogenic significance of local TNF release in immune renal disease accompanied by prominent glomerular macrophage accumulation.

Spontaneous release of tumor necrosis factor alpha by isolated renal glomeruli and cultured glomerular mesangial cells.

Although mononuclear phagocytes were once considered the sole source of tumor necrosis factor alpha (TNF), it is now understood that other cell types, including T and B lymphocytes, may be stimulated to produce this factor. Herein we describe the release of a cytotoxic activity in vitro by isolated rat glomeruli and cultured glomerular mesangial cells. Immunoperoxidase staining with monoclonal antibodies against Ia and leukocyte common antigen-documented cultured mesangial cell populations were free of mononuclear phagocytes. Cytotoxic activities generated by isolated glomeruli and mesangial cell cultures eluted on gel chromatography in two peaks corresponding to molecular weights of 17 and 40 kDa and were fully inhibitable by anti-recombinant murine TNF antiserum. These data strongly suggest that intrinsic glomerular mesangial cells contribute to TNF release by intact glomeruli. Intraglomerular generation of TNF and perhaps other cell types may bear upon the pathogenesis of immune glomerular injury.

Mechanisms of glomerular injury in experimental immune nephritis. I. Tumor necrosis factor is released by renal glomeruli of nephritic rats.

Cytotoxic activity expressed by renal glomeruli of LEW rats with the accelerated autologous form of nephrotoxic serum nephritis (AA-NTSN) was assessed using the lymphotoxin (LT) sensitive line aL929. Glomeruli isolated on day 3 following nephritis induction were much more cytotoxic for aL929 in coculture than glomeruli of unmodified LEW (p less than 0.0025). Such a cytolysis was due to a soluble factor eluted on gel chromatography in a single peak corresponding to molecular weight (MW) of 40-45 kDa. The cytotoxic activity, harvested in 24-hour culture supernatants of nephritic glomeruli (NGS) and the chromatographic peak were totally inhibitable by antiserum neutralizing recombinant murine tumor necrosis factor alpha (rMuTNF). An abundant glomerular macrophage accumulation on day 3 and reduction of cytotoxicity (42.3%, p less than 0.01) upon irradiation limiting the mononuclear phagocyte infiltrate suggest that macrophages are at least partly responsible for TNF production by nephritic glomeruli. This study provides the initial documentation on generation of TNF in glomerular inflammatory injury induced by immune reaction.

Mechanisms of glomerular injury in experimental immune nephritis. II. Effect of a platelet activating factor receptor antagonist in an autologous nephritis model.

The role of Platelet Activating Factor (PAF) in experimental immune glomerulonephritis was assessed by administering the specific PAF receptor antagonist CV-3988 to inbred LEW rats with the Accelerated Autologous Nephrotoxic Serum Nephritis (AA-NTSN). Intravenous administration of CV-3988 caused a marked and sustained reduction in albuminuria and renal histopathological changes. Conversely, although CV-3988 appeared to modulate the fall in glomerular filtration rate (GFR) in the AA-NTSN, this trend was not statistically significant. Renal glomeruli isolated on day 1 after nephritis induction spontaneously released 16.9 +/- 2.2 ng of PAF per 200 glomeruli, while in glomeruli of healthy rats this secretion was virtually undetectable. The administration of CV-3988 to rats with AA-NTSN did not affect the following: binding of intravenously injected sheep anti-rat glomerular basement membrane (GBM) antibody; levels of autologous antibody to sheep immunoglobulin G; the functional integrity of circulating neutrophils. We conclude that local PAF generation and release is intimately linked with the pathogenesis of glomerular injury in this form of immune disease.

Effects of tumor necrosis factor on glomerular mesangial and epithelial cells in culture.

We have previously documented the importance of tumor necrosis factor (TNF) alpha in the pathogenesis of nephrotoxic-serum nephritis in rats. In this study, we evaluated the possible relevance of the well-established cytocidal TNF activity to the mechanism of glomerular injury by assessing sensitivity of rat mesangial and epithelial cell populations to recombinant murine TNF alpha (rMuTNF). Radiolabelled confluent mesangial cell cultures that were incubated with rMuTNF released significantly more 3H-thymidine than control monolayers (maximum specific release was 11.4 +/- 4.9% at 1,000 pg/ml of rMuTNF). rMuTNF was, however, approximately 1,000-fold less cytolytic in mesangial cells than in the lymphotoxin-sensitive L929 cell line. Conversely, glomerular epithelial cells were not affected by exposure to rMuTNF under the same conditions. These results suggest that the cytolytic effect of TNF may contribute to glomerular injury in nephrotoxic-serum nephritis.

Captopril in temporary, non-dialytic management of pulmonary edema in end-stage renal disease.

The only effective management of life-threatening hypervolemia in course of terminal renal failure is dialysis or hemofiltration. Nonetheless we succeeded in attenuating hypervolemic pulmonary edema utilizing low doses of Captopril in three patients awaiting entry into the maintenance hemodialysis program. The drug added to diuretic and, in two cases, digitalis therapy enabled pharmacologic management of patients volume overload for 12-25 days before the dialysis treatment could be started. No further decline in renal function or other side effects of Captopril were encountered. We conclude that Captopril may be life-saving in settings requiring pharmacologic relief of uremic pulmonary edema.