IV arginine therapy increases mitochondrial activity and decreases oxidative stress in children with SCD and vaso-occlusive pain.
A dose-dependent impact of arginine therapy on mitochondrial function is a novel mechanism of action not previously described in SCD.
Altered mitochondrial function occurs in sickle cell disease (SCD), due in part to low nitric oxide (NO) bioavailability. Arginine, the substrate for NO production, becomes acutely deficient in SCD patients with vaso-occlusive pain episodes (VOE). To determine if arginine improves mitochondrial function, 12 children with SCD-VOE (13.6 ± 3 years; 67% male; 75% hemoglobin-SS) were randomized to 1 of 3 arginine doses: (1) 100 mg/kg IV 3 times/day (TID); (2) loading dose (200 mg/kg) then 100 mg/kg TID; or (3) loading dose (200 mg/kg) followed by continuous infusion (300 mg/kg per day) until discharge. Platelet-rich plasma mitochondrial activity, protein expression, and protein-carbonyls were measured from emergency department (ED) presentation vs discharge. All VOE subjects at ED presentation had significantly decreased complex-V activity compared to a steady-state cohort. Notably, complex-V activity was increased at discharge in subjects from all 3 arginine-dosing schemes; greatest increase occurred with a loading dose (P < .001). Although complex-IV and citrate synthase activities were similar in VOE platelets vs steady state, enzyme activities were significantly increased in VOE subjects after arginine-loading dose treatment. Arginine also decreased protein-carbonyl levels across all treatment doses (P < .01), suggesting a decrease in oxidative stress. Arginine therapy increases mitochondrial activity and reduces oxidative stress in children with SCD/VOE. This trial was registered at www.clinicaltrials.gov as #NCT02536170.