In vitro and in vivo TNFα synthesis modulation by methylguanidine, an uremic catabolyte

Abstract

This study was performed in order to examine whether the uraemic toxin, methylguanidine (MG), can modulate tumor necrosis factor α (TNFα) release by activated macrophages. In this study we have evaluated the ability of MG to influence TNFα release in vitro, in Escherichia coli lypopolysaccharide- (LPS)-stimulated J774 cells preincubated overnight with MG, and in vivo in rats treated with MG before and after LPS challenge. Parallel experiments employing N G-nitro-L-arginine methyl esther (L-NAME) were also carried out for comparison. The effect of LPS (6 × 10 3 u/ml) on TNFα release by J774, following overnight incubation with MG or L-NAE (1 mM), was examined 3 hours after LPS challenge. LPS-stimulated J774 released 287.83 ± 88 u/ml TNFα into the culture medium. MG (1 mM) significantly inhibited TNFα release by 73 % (P < .05). L-NAME (1 mM) significantly inhibited TNFα release too by 72.88 % (P < 0.05). The effect of MG and L-NAME have been also studied in vivo. Serum TNFα levels in LPS treated rats 2 h after LPS challenge were 88.33 ± 31.7 u/ml as compared to the serum TNFα levels of control rats (undetectable). Treatment of rats with MG (30 mg/kg, i.p.) strongly and significantly reduced TNFα release (98.71 % inhibition; with P < 0.001); in the same experimental setting L-NAME (10 mg/kg, i.p.) also significantly reduced TNFα serum levels (76.47 % inhibition; with P < 0.01). These results could indicate that immunedisfunction related to uremia may be related to the inhibitory capability of uremic catabolyte, MG, on TNFα synthesis and release.