Tetrahydrobiopterin Supplementation Improves Endothelial Function But Does Not Alter Aortic Stiffness in Patients...

Area of Science:

• Cardiovascular Medicine
• Rheumatology
• Pharmacology

Background:

• Rheumatoid arthritis (RA) is linked to higher cardiovascular disease (CVD) risk.
• Endothelial dysfunction and aortic stiffening are potential mechanisms for RA-related CVD.
• Tetrahydrobiopterin (BH4) may improve endothelial function by enhancing nitric oxide synthase activity.

Purpose of the Study:

• To investigate the effects of BH4 supplementation on endothelial function and aortic stiffness in RA patients.
• To determine if BH4 can improve endothelial nitric oxide synthase (eNOS) coupling.
• To assess the impact of BH4 on aortic pulse wave velocity (PWV) as a measure of aortic stiffness.

Main Methods:

• Two randomized, double-blinded, placebo-controlled crossover studies were conducted.
• Participants received either acute (single dose) or short-term (1-week) BH4 (400 mg) or placebo.
• Flow-mediated dilatation (FMD) and aortic pulse wave velocity (PWV) were measured.

Main Results:

• Acute BH4 supplementation significantly improved flow-mediated dilatation (FMD) compared to placebo (P=0.03).
• One-week BH4 treatment also enhanced endothelial function (P=0.02), while placebo had no effect.
• Neither acute nor short-term BH4 administration altered aortic pulse wave velocity (PWV).

Conclusions:

• Oral BH4 supplementation effectively improves endothelial function in RA patients.
• BH4 does not appear to reduce aortic stiffness in this cohort.
• Endothelial dysfunction and aortic stiffness may be parallel consequences of RA-related inflammation rather than causally linked.