Recombinant thrombomodulin alleviates oxidative stress without compromising host resistance to infection in rats infected with methicillin-resistant Staphylococcus aureus

Recombinant thrombomodulin (rTM) has been used for treatment of sepsis-associated disseminated intravascular coagulation. Recent studies have suggested that anticoagulant therapy might dampen the protective role of immunothrombosis. We examined if rTM might worsen infectious diseases. Male Sprague–Dawley rats with jugular-vein catheterization were divided into three groups: no anticoagulation; rTM pretreatment; rTM treatment at 6 h. Live methicillin-resistant Staphylococcus aureus (MRSA) was inoculated into the tail vein of rats. rTM was administered into the jugular-vein catheter before or 6 h after MRSA inoculation, while an equal volume of saline was administered in the no-anticoagulation group. Blood samples were collected from the jugular-vein catheter before, 6 h and 12 h after MRSA inoculation. Tissue samples were collected from anesthetized rats when moribund or 18 h after MRSA inoculation. The survival rate of rats in the no-anticoagulation group, rTM pretreatment group, and rTM treatment at 6-h group was 50%, 25%, and 75%, respectively. Bacterial burden in blood, lung, liver, and spleen was neither increased nor decreased in rats treated with rTM. The ratio of bacteria found in the extravascular space to those in the intravascular space was increased in rats treated with rTM although the statistical power for this was low because of the small sample size. Metabolomics analysis revealed that rTM treatment alleviated oxidative stress, as evidenced by the decrease in levels of oxidized glutathione with reference to reduced glutathione. rTM did not promote bacterial propagation but alleviated oxidative stress in our rat model of bloodstream infection with MRSA. Further large-scale studies are needed to confirm these findings.