Endothelial Cell Production of Nitrogen Oxides in Response to Interferon   in Combination With Tumor Necrosis Factor, Interleukin-1, or Endotoxin

Abstract

Clinical studies using biological response modifiers in cancer therapy have shown that the major dose-limiting toxic effects are hypotension and diffuse microvascular leakage. The cause and pathophysiology of this hypotension remains unknown. Previous experiments have demonstrated that a number of cell types, including endothelial cells, neutrophils, and macrophages, can secrete a potent hypotensive agent--endothelium-derived relaxing factor, which has recently been identified as nitric oxide. In this study, we tested interferon gamma, tumor necrosis factor, interleukin-1, interleukin-2, muramyl dipeptide, and endotoxin for their effects on production of nitrogen oxides by endothelial cells. Interferon gamma, in combination with tumor necrosis factor, interleukin-1 (IL-1), or endotoxin, induced murine brain endothelial cells to secrete nitrites (20-45 microM within 48 hr), which are breakdown products of nitric oxide. Nitrite production was blocked by incubation of endothelial cells in medium without L-arginine, a substrate for nitric-oxide synthase. Accumulation of nitrites was also inhibited by addition of NG-monomethyl-L-arginine (L-NMMA), which acts as a competitive inhibitor of this enzyme. The inhibitory effects of L-NMMA were reversed by addition of excess L-arginine. These results suggest (a) that endothelial cells produce nitric oxide in response to immunomodulators and (b) that endothelial cell-derived nitric oxide plays a role in the development of hypotension in patients treated with tumor necrosis factor or interleukins. Furthermore, administration of substrate analogues such as L-NMMA may favorably alter the toxicity associated with these immunomodulators and result in a higher maximum tolerated dose, with subsequent improvement in the antitumor activity.

Cytotoxic action of IL‐1β against pancreatic islets is mediated via nitric oxide formation and is inhibited by NG‐monomethyl‐l‐arginine

“…And it was shown very recently that the 1L-1/~-induced inhibition of insulin secretion is also reversible by adding NMA [14,15]. Islets contain a dense capillary network [I 6] and endothelial cells have been shown to be inducible for generating large amounts of nitric oxide by cytokines, eSl~-cially IL-1]~ in synergny with TNF~ and/or IFN-7 [17][18][19][20]. Indeed, we find that the slightly enhanced lysis seen in the presence of both IL-I~ and TNF was also completely blocked by NMA.…”

Synthesis and biological effects of NO in malignant glioma cells: modulation by cytokines including CD95L and TGF-β dexamethasone, and p53 gene transfer

“…Inducible NOS (iNOS) is calcium-independent and produces large amounts of NO which may mediate cGMP-independent cytotoxicity against microorganisms and tumor cells (Stuehr and Nathan, 1989). iNOS is found in a variety of cells such as macrophages (Marletta et al, 1988), endothelial cells (Kilbourn and Belloni, 1990) and glial cells . While all three types of NOS may be expressed in astrocytomas (Cobbs et al, 1995), expression of iNOS was only observed in high-grade tumors and mainly restricted to endothelial cells within the tumor.…”

Role of tumour necrosis factor in the induction of nitric oxide synthase in a rat model of endotoxin shock

“…Like LPS, TNF also induces the calcium-independent isoform of NOS in vitro (Drapier et al, 1988;Kilbourn & Belloni, 1990). Systemic administration of TNF increases NO production (Kosaka et al, 1992) and causes NO-mediated vasodilatation and vascular hyporeactivity to vasoconstrictors in vivo (Vicaut & Baundry, 1992) and ex vivo (Takahashi et al, 1992;Foulkes & Shaw, 1992).…”