Peroxynitrite Enhances the Ability of Salmonella dublin to Invade T84 Monolayers

Abstract

In the intestine, epithelial cells continually produce and secrete low levels of nitric oxide (NO). Salmonella sp. invade epithelium by responding to environmental stimuli. The aims of this study were to determine the effect of reactive nitrogen intermediates (RNIs) on S. dublin and S. typhimurium growth and invasion of T84 epithelial monolayers. Intracellular NO formation was inhibited by 7-nitroindazole (7-NI) or N(G)-monomethyl-L-arginine, monoacetate (L-NMMA); extracellular NO and peroxynitrite were scavenged with ferro-hemoglobin or urate. The effect of authentic peroxynitrite (ONOO-); 3-morpholino-sydnonimine (SIN-1), which releases ONOO- via NO and superoxide; spermine NONOate, which releases only NO; or superoxide generated by xanthine oxidase and pterin on S. dublin and S. typhimurium growth and invasion were examined. Inhibition of NO synthesis and scavenging of extracellular NO or peroxynitrite reduced S. dublin invasion into T84 monolayers and enhanced bacterial growth. Pre-exposure of S. dublin to ONOO- and SIN-1 increased subsequent bacterial invasion into T84 monolayers. Conversely, exposure of bacteria to spermine NONOate or superoxide did not affect S. dublin invasion. In contrast, S. typhimurium invasion was not affected by pre-treatment with NO donors. In conclusion, exposure of S. dublin to ONOO- enhances the ability of the bacteria to invade epithelial cells. These results suggest that luminal ONOO- may have a novel role as an extracellular signal between invasive bacteria and epithelial cells.

Differential sensitivity of oligodendrocytes and motor neurons to reactive nitrogen species: implications for multiple sclerosis

“…In light of the fact that high flux NO seen in pathological situations produces RNS with resultant 3NY formation (Tamir et al. 1993, 1996; Cornish et al. 2002), and cell death (Estevez et al.…”

“…1a). For the challenge NO dose, we used 10 lM final concentration spermine-NONOate, which donates NO at a higher flux (Cornish et al 2002) of 110 pmol/s (high dose) (Fig. 1a).…”

“…In light of the fact that high flux NO seen in pathological situations produces RNS with resultant 3NY formation (Tamir et al 1993(Tamir et al , 1996Cornish et al 2002), and cell death (Estevez et al 1998(Estevez et al , 2000Ischiropoulos and Beckman2003;Prat and Antel 2005;Jack et al 2007;Pacher et al 2007) we wanted to ask if spermine-NONOate, unlike DETA-NONOate, does indeed show greater toxicity. We exposed NSC34D (motor neuron cell line) to a dose-response curve of DETA versus spermine and found a significant difference of cell survival at the highest dose (104% ± 10 vs. 16% ± 8 (n = 4), p < 0.001) ( Fig.…”

Mitigation of peroxynitrite‐mediated nitric oxide (NO) toxicity as a mechanism of induced adaptive NO resistance in the CNS

“…It has been demonstrated that NO at a high flux produces RNS with resultant 3NY formation (Tamir et al. 1993, 1996) and that spermine‐NONOate, unlike DETA‐NONOate, does donate NO at a high flux (Cornish et al. 2002).…”

“…1a, cytotoxic). It has been demonstrated that NO at a high flux produces RNS with resultant 3NY formation (Tamir et al 1993(Tamir et al , 1996 and that spermine-NONOate, unlike DETA-NONOate, does donate NO at a high flux (Cornish et al 2002). We asked if pre-treatment of motor neurons with low dose NO induced NO resistance to normally cytotoxic doses of NO (Fig.…”