Microfluidic system for immune cell activation and inflammatory cytokine profiling: Application to screening of dietary supplements for anti-inflammatory properties.

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A versatile and reconfigurable microfluidic chip has been fully in-house fabricated and tested for immune cell culture, activation, and quantification of multi-cytokine secretion. The chip comprises three vertically stacked fluidic layers for perfusion, cell culture and cytokine capture, and quantification, respectively. The perfused media were separated from the cell culture by employing a biomimetic membrane as a model of the intestinal epithelial layer. Time-resolved detection and quantification of several secreted cytokines were enabled by an array of parallel channels, which are interfaced with the cell culture by a porous membrane. Each channel hosts magnetic beads conjugated with a specific antibody against the cytokine of interest. Magnetic bead-assisted agitation enables homogenization of the cell culture supernatant and perfusion of the cytokines through the bottom immune assay channels. As a proof of concept, THP-1 monocytic cells and their induced macrophages were used as a model of immune-responsive cells. The cells were sequentially stimulated by lipopolysaccharides and two dietary supplements, namely, docosahexaenoic acid (DHA) and curcumin, which are known to possess inflammasome-modulating activity. Both DHA and curcumin have shown anti-inflammatory effects by downregulating the secretion of TNFα, IL-6, IL-1β, and IL-10. Treatment of the cells with DHA and curcumin together lowered the TNFα secretion by ∼54%. IL-6 secretion was lowered upon cell treatment with curcumin, DHA, or DHA and curcumin co-treatment by 69%, 78%, or 67%, respectively. IL-1β secretion was lowered by 67% upon curcumin treatment and 70% upon curcumin and DHA co-treatment. IL-10 secretion was also lowered upon treating the cells with DHA, curcumin, or DHA and curcumin together by 7%, 53%, or 54%, respectively. The limit of the detection of the assay was determined as 25 pg/ml. Four cytokine profiling was demonstrated, but the design of the chip can be improved to allow a larger number of cytokines to be simultaneously detected from the same set of cells.