Coffee (Coffea spp.) is one of the most important agricultural commodities, being widely consumed in the world. Various beneficial health effects of coffee have been extensively investigated, but data on habitual coffee consumption and its bio-physiological effect have not been clearly explained as well as it is not proved the cause and effect between drinking coffee and its bio-physiological reactions. We made the dialyzed coffee extract (DCE), which is absorbable through gastrointestinal tract, in order to elucidate the cellular effect of whole small coffee molecules. RAW 264.7 cells, a murine macrophage lineage, were directly treated with DCE, i.e., DCE-2.5 (equivalent to 2.5 cups of coffee a day), DCE-5, and DCE-10, for 12 hours, and their protein extracts were examined by immunoprecipitation high performance liquid chromatography (IP-HPLC). RAW 264.7 cells differently expressed the inflammation-related proteins depending on the doses of DCE. RAW 264.7 cells treated with DCE showed marked increase of cathepsin C, cathepsin G, CD20, CD28, CD31, CD68, indicating the activation of innate immunity. Particularly, the macrophage biomarkers, cathepsin G, cathepsin C, CD31, and CD68 were markedly increased after DCE-5 and DCE-10 treatments, and the lymphocyte biomarkers, CD20 and CD28 were consistently increased and became marked after DCE-10 treatment. On the other hand, RAW 264.7 cells treated with DCE showed consistent increase of IL-10, an anti-inflammatory factor, but gradual decreases of different pro-inflammatory proteins including TNFα, COX-2, lysozyme, MMP-2, and MMP-3. In particular, the cellular signaling of inflammation was gradually mitigated by the reduction of TNFα, COX-2, IL-12, and M-CSF, and also the matrix inflammatory reaction was reduced by marked deceases of MMP-2, MMP-3, and lysozyme. These anti-inflammatory expressions were consistently found until DCE-10 treatment. Therefore, it is presumed that DCE may have dynamic effects of innate immunity activation and pro-inflammation suppression on RAW264.7 cells simultaneously. These effects were consistently found in the highest dose of coffee, DCE-10 (equivalent to 10 cups of coffee a day in man), that might imply the small coffee molecules were accumulated in RAW 264.7 cells after DCE-10 treatment and produce synergistic cytokine effects for innate immunity activation and anti-inflammatory reaction concurrently.

In order to perform the biological investigation of coffee extract containing different molecules, it would be necessary to develop in vitro experimental system rather than animal experiment. Although the animal experiment treated via oral intake or intravenous injection may disclose the whole systemic effect, the in vitro cell culture experiment would be more convenient to analyze direct cellular effect of coffee extract than animal experiment. Therefore, this study was aimed to develop a dialysis method for the crude coffee extract to perform the biological investigation using murine macrophage cell line, RAW 264.7. First of all, the RAW 264.7 cells treated with dialyzed coffee extract were observed, and subsequently their protein extracts were analyzed by gel filtration chromatography, thin layer chromatography, and immunoprecipitation high performance liquid chromatography (IP-HPLC). Resultantly, it was found that the low dose (20μg/mL) of dialyzed coffee extract, about 5 cups of ordinary coffee drinking for human adult, enhanced the growth of RAW 264.7 cells by increased expression of β-actin and Ki-67, and also induced the anti-inflammatory effect by decreased expression of NFkB, TNFα, and LC3 contrast to the high dose (40μg/mL) of dialyzed coffee extract. The low dose of dialyzed coffee extract produced almost no harmful effect on RAW cell culture for 12 hours, rather than it produced stimulatory effect on RAW cells by increasing the cell number and enhancing the protein expression of β-actin, Ki-67. Therefore, it was thought that the low dose of dialyzed coffee extract is applicable to cell culture experiment without difficult purification procedures of coffee elements. In addition, as the contrast cellular effect between the low and high dose of coffee extract was found in this study, it was also presumed that the low dose of coffee extract may play an important role in the inflammatory reaction of murine macrophages.