Effects of tomato extract on cytokine profile of human Peripheral Blood Mononuclear Cells (PBMCs)

Objective This study was aimed to evaluate the effect of the addition of tomato extract (TE) on cytokine production. Material and Methods Human PBMCs (n=7, independent samples) were isolated by Ficoll‐Hypaque gradient centrifugation and cultured with PHA (7μg/ml) and LPS (1.5μg/ml) for 48hs to stimulate cytokine production. TE was achieved by means of saponification and solvent extraction (hexane) in order to obtain the non‐polar compounds naturally included in tomato. A concentration step and subsequent re‐dissolution in ethanol was made (final concentrations <1% in culture cells). In this TE, lycopene and vitamin E are main bioactive compounds. We focused on α‐tocopherol. Four groups were considered: PBMCs + PHA/LPS + 1, 10 or 20μM of α‐tocopherol from TE (PBMC‐1, PBMC‐10 and PBMC‐20 groups, respectively) and PBMCs + PHA/LPS used as the control group (C). IFN‐γ, TNF‐α, IL‐2, IL‐17A, IL‐1β, IL‐4, IL‐13 and IL‐10 were measured in culture supernatants by flow‐cytometry (CBA, EMD Millipore). Statistics were performed using Univariate (LSD Fisher test) and Multivariate Analysis (HCA). Results A dose‐dependent response to TE was observed ( figure 1). Regarding cytokine production, IFN‐γ and IL‐10 levels were significantly lower (p=0.04 and p=0.02, respectively) in PBMC‐20 than in C. No significant differences were found in the other cytokines. Although TNF‐α showed no significant difference among groups, TNF‐α/IL‐10 ratio increased up to 60% due to the decrease in IL‐10 production in the presence of increased amounts of TE. As observed in figure 2, for a given concentration of TNF‐α, IL‐10 values are lower in the presence of higher amounts of TE (PBMC‐10 and PBMC‐20). Another pro‐inflammatory cytokine, such as IL‐1β showed a similar pattern ( figure 3). These findings may indicate a modulation of TE on the pro‐inflammatory cytokine response. The homeostatic relationship between IFN‐γ and TNF‐α is well‐known. There was a change when TE was added. While in C IFN‐γ/TNF‐α levels were 1.46, in PBMC‐20 this ratio decreased to 0.71 due to a strong decrease in IFN‐γ levels (p=0.01). In this regard, pro‐inflammatory/anti‐inflammatory cytokine ratio was significantly higher (p=0.02) for PBMC‐20 vs. C, showing PBMC‐10 intermediates values, which indicates an anti‐inflammatory state. Conclusion In the in vitro system performed in this study, a physiological amount of α‐tocopherol (20μM) and the corresponding level of lycopene from tomato have shown to be able to produce an anti‐inflammatory effect.