Significance of oxygen intermediates-superoxide ratio in tissue injuries of several disorders

Abstract

It has been elucidated that phagocyte-released oxygen intermediates (O-2, H2O2, OH⋅, 1O2) (OI) which are excessively generated to fuse invading agents in their phagosomes induce auto-oxidative damage such as tissue injury in several human cells in vivo. On the other hand, superoxide dismutase (SOD), oxygen-scavenging enzyme is produced in every human cell to prevent itself from auto-oxidative damage by increasingly released OI. Recently, there have been reports suggesting the auto-oxidative damage only from the result of a decrease in SOD activity. In this study, the authors assessed both the capacity for generating OI by neutrophils and SOD activity in blood including serum and blood cells of the patients with various diseases to calculate OI/SOD ratio, by which tissue injury induced by an increase in OI in every disease was investigated and discussed. Patients with dermatitis herpetiformis in whom both an increase in OI generation and a decrease in SOD activity were found, showed the highest OI/SOD ratio. The patients with mucocutano lymphnode syndrome (within 5 days after onset) and rheumatoid arthritis (but only in synovia) in whom an increase of OI generation was not accompanied by that of SOD activity, showed nextly high OI/SOD ratio. In the cases of active Behcet's disease, severe cement dermatitis and untreated, active SLE with similar behaviours, the ratio was also elevated. Since in these patients, marked tissue injury has been reported to be found, the present study revealed that the examination of the difference between OI levels and SOD activity is closely related to the tissue injury analysis.In the patients with bacterial infections an increase of both OI generation and SOD activity was observed. And the cases of viral infections and various cancers showed a slight decrease of both OI production and SOD activity. In the patients with these three disorders, OI/SOD ratio was within normal levels. Asymptomatic heavy smokers with more than 40 pieces of cigarettes a day for 20 years of longer showed a remarkable increase in OI generation sufficiently accompanied by enhanced SOD activity. However, two cases which had been considered to be asymptomatic but were revealed lung cancer 7-10 months later, had not shown an increase in SOD activity, leading to a markedly elevated ratio of OI/SOD. OI/SOD ratio which the authors proposed in this study seems to work as an indicator of tissue injury induced by increasingly produced OI and further possibly predict the asymptomatic individuals in pre-cancer stage.