A Pharmacologic "Stress Test" for Assessing Select Antioxidant Defenses in Patients with CKD.

BACKGROUND AND OBJECTIVES: Oxidative stress is a hallmark and mediator of CKD. Diminished antioxidant defenses are thought to be partly responsible. However, there is currently no way to prospectively assess antioxidant defenses in humans. Tin protoporphyrin (SnPP) induces mild, transient oxidant stress in mice, triggering increased expression of select antioxidant proteins (e.g., heme oxygenase 1 [HO-1], NAD[P]H dehydrogenase [quinone] 1 [NQO1], ferritin, p21). Hence, we tested the hypothesis that SnPP can also variably increase these proteins in humans and can thus serve as a pharmacologic "stress test" for gauging gene responsiveness and antioxidant reserves. DESIGN: , setting, participants, & measurementsA total of 18 healthy volunteers and 24 participants with stage 3 CKD (n=12; eGFR 30-59 ml/min per 1.73 m2) or stage 4 CKD (n=12; eGFR 15-29 ml/min per 1.73 m2) were injected once with SnPP (9, 27, or 90 mg). Plasma and/or urinary antioxidant proteins were measured at baseline and for up to 4 days post-SnPP dosing. Kidney safety was gauged by serial measurements of BUN, creatinine, eGFR, albuminuria, and four urinary AKI biomarkers (kidney injury molecule 1, neutrophil gelatinase-associated lipocalin, cystatin C, and N-acetyl glucosaminidase). RESULTS: Plasma HO-1, ferritin, p21, and NQO1 were all elevated at baseline in CKD participants. Plasma HO-1 and urine NQO1 levels each inversely correlated with eGFR (r=-0.85 to -0.95). All four proteins manifested statistically significant dose- and time-dependent elevations after SnPP injection. However, marked intersubject differences were observed. p21 responses to high-dose SnPP and HO-1 responses to low-dose SnPP were significantly suppressed in participants with CKD versus healthy volunteers. SnPP was well tolerated by all participants, and no evidence of nephrotoxicity was observed. CONCLUSIONS: SnPP can be safely administered and, after its injection, the resulting changes in plasma HO-1, NQO1, ferritin, and p21 concentrations can provide information as to antioxidant gene responsiveness/reserves in subjects with and without kidney disease. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: A Study with RBT-1, in Healthy Volunteers and Subjects with Stage 3-4 Chronic Kidney Disease, NCT0363002 and NCT03893799.

Comparison between desferrioxamine and combined therapy with desferrioxamine and deferiprone in iron overloaded thalassaemia patients.

Desferrioxamine (DFX) alone (40-50 mg/kg/d s.c. over 8-12 h, five times weekly) was compared with combined DFX twice weekly and deferiprone (75 mg/kg/d) over 12 months in previously poorly chelated thalassaemia patients. Serum ferritin fell from 5506 +/- 635 microg/l (mean +/- SEM) to 3998 +/- 604 microg/l (P < 0.001; n = 14) in the DFX group and from 4153 +/- 517 microg/l to 2805 +/- 327 microg/l in the combined group (P < 0.01; n = 11). Deferiprone plus DFX produced a greater mean urine iron excretion (1.01 mg/kg/24 h) than iron intake from blood transfusion in each patient. Main side-effects were skin reactions (DFX alone), nausea and arthralgia (combined therapy). As chelation therapy, the combined protocol was as effective as DFX five times weekly.