Figure 4.

Chlorogenic acid isomers inhibit the expression of proinflammatory cytokines induced by VD₃ in HEKn/THP-1 co-culture. HEKn were seeded on upper insert chambers, and THP-1 was seeded on lower chamber in the two-compartment transwell system for 24 h. Upper insert was pretreated with 1, 10, or 50 µM isochlorogenic acids A and isochlorogenic acid C, respectively, for 1 h, followed by treatment with 200 nM VD₃. After 72 h incubation, the secreted pro-inflammatory cytokines (TNF-α, IL-1β) were measured by ELISA. The results are expressed as mean ± standard deviation (SD) (n = 3). * p < 0.01 vs. vehicle control; ** p < 0.05 vs. VD₃-treated control; *** p < 0.01 vs. VD₃-treated control.