Purpose: Coffee consumption has been associated with various health benefits; however, the underlying biological mechanisms remain poorly understood. In particular, the acute effects of coffee on circulating cytokines and the specific role of caffeine compared with the whole coffee matrix are still insufficiently characterised in humans. To our knowledge, no previous human study has directly compared immune modulation by coffee versus caffeine alone. We therefore aimed to elucidate the effect of a usual caffeine dose of 130 mg on postprandial cytokine secretion, and whether responses differ between coffee and pure caffeine. Methods: In a randomized pilot trial, ten healthy volunteers completed three test days receiving either a coffee brew, an aqueous caffeine solution (each 130 mg caffeine/100 ml), or water. Quantitative analysis of caffeine was performed with UHPLC-MS/MS, immune markers were measured by a multiplex immunoassay. Results: Our study demonstrates that both caffeine and coffee consumption influence the immune homeostasis, albeit with notable differences on cytokine secretion. Pure caffeine induced a higher anti-inflammatory response, as evidenced by the significant decrease in pro-inflammatory cytokines such as IL-17 A, IL-12p70, and IL-2 compared to coffee and water. The integrated response on the immune system is exemplified by the decrease of the pro-inflammatory IFN-γ (0.649 ± 0.068) and the anti-inflammatory IL-10 (0.478 ± 0.043), vs. baseline, respectively. Conclusion: These findings provide novel in vivo evidence that usual coffee and caffeine acutely affects cytokine responses differently in healthy individuals. In conclusion, our study addresses an important gap regarding the immune properties of coffee and suggests that bioactive compounds beyond caffeine contribute substantially to its immunological effects.

Background: Microbeam radiation therapy (MRT) is an advanced preclinical approach in radiotherapy that utilizes spatially fractionated dose distributions by collimating x-rays into micrometer-wide, planar beams. While the benefits of temporal fractionation are well established and widely incorporated into conventional radiotherapy protocols, the interplay between MRT and temporal dose fractionation remains largely unexplored. In this study, we investigate the effects of combining temporal and spatial dose fractionation by assessing clonogenic cell survival following temporally fractionated MRT with varying irradiation angles, compared to conventional broad-beam (BB) irradiation. Methods: A lung tumor cell line (A549) and a normal lung cell line (MRC-5) were irradiated with a total number of four fractions with a 24 h interval between each fraction. We compared a temporally fractionated BB regime to two temporally fractionated MRT schemes with either overlapping MRT fields or MRT fields with a 45° rotation per fraction. Subsequently, the clonogenic cell survival assay was used by analyzing the corresponding survival fractions (SFs). Results: The clonogenic survival of A549 tumor cells differed significantly between microbeam radiation therapy with rotation (MRT + R) and overlapping MRT. However, neither MRT + R nor overlapping MRT showed statistically significant differences compared to the broad-beam (BB) irradiation for A549. In contrast, the normal tissue cell line MRC-5 exhibited significantly higher clonogenic survival following both MRT + R and overlapping MRT compared to BB. Conclusions: This study demonstrates that combining temporal and spatial fractionation enhances normal tissue cell survival while maintaining equivalent tumor cell kill, potentially increasing the therapeutic index. Our findings support the feasibility of delivering temporally fractionated doses using different MRT modalities and provide clear evidence of the therapeutic benefits of temporally fractionated MRT.