Cocoa Flavonols and Procyanidins Promote Transforming Growth Factor-β1 Homeostasis in Peripheral Blood Mononuclear Cells1

Evidence suggests that certain flavan-3-ols and procyanidins (FP) can have a positive influence on cardiovascular health. It has been previously reported that FP isolated from cocoa can potentially modulate the level and production of several signaling molecules associated with immune function and inflammation, including several cytokines and eicosanoids. In the present study, we examined whether FP fractions monomers through decamers modulate secretion of the cytokine transforming growth factor (TGF)-β1 from resting human peripheral blood mononuclear cells (PBMC). A total of 13 healthy subjects were studied and grouped according to their baseline production of TGF-β1. When cells from individuals with low baseline levels of TGF-β1 (n = 7) were stimulated by individual FP fractions (25 μg/ml), TGF-β1 release was enhanced in the range of 15%–66% over baseline (P < 0.05; monomer, dimer, and tetramer). The low-molecular-weight FP fractions (≤pentamer) were more effective at augmenting TGF-β1 secretion than their larger counterparts (≥hexamer), with the monomer and dimer inducing the greatest increases (66% and 68%, respectively). In contrast to the above, TGF-β1 secretion from high TGF-β1 baseline subjects (n = 6) was inhibited by individual FP fractions (P < 0.05; trimer through decamer). The inhibition was most pronounced with trimeric through decameric fractions (28%–42%), and monomers and dimers moderately inhibited TGF-β1 release (17% and 23%, respectively). Given the vascular actions associated with TGF-β1, we suggest that in healthy individuals, homeostatic modulation of its production by FP offers an additional mechanism by which FP-rich foods can potentially benefit cardiovascular health.