Secretion analysis of invading process between Salmonella typhimurium and HT-29 intestinal epithelial cells on the microfluidic chip

Abstract

A contact co-culture model of bacteria and cells on the microfluidic chip with arrayed circular chambers was established to simulate the process of Salmonella typhimurium (S. typhimurium) invading HT-29 intestinal epithelial cells in this paper. The interaction process could be observed and detected in situ on the designed microchip. By optimizing the structure and size of chambers and microchannels, the microchip was more suitable for microscopic in-situ observation. The cell viability, morphology, cytoskeleton and secretions were detected during the interaction process of S. typhimurium invading HT-29 intestinal epithelial. In the experiments, cells formed multicellular aggregates, and cell cytoskeleton rearranged to form giant pinocytosis after exposure to S. typhimurium. It was shown that cell viability was continuously decreased during the process. Furthermore, it was also illustrated that cell viability was positively related to cytoskeleton damage and cell cytoskeleton regulated cell morphology. The cell secretions IL-8 in the co-culture supernatants were measured by enzyme-linked immunosorbent assay (ELISA). It was shown that the level of IL-8 increased rapidly when S. typhimurium invaded HT-29 intestinal epithelial cells, reached a peak of 4.45 pg/mL at 3 h, and then continuously came down until recovered to the baseline level of 1.04 pg/mL at 12 h. The designed microfluidic chip could provide a unique way to study the interaction of pathogen invaded cells and important information for the analysis of bacterial infection and other related research.