Mechanical Stimuli Affect Escherichia coli Heat-Stable Enterotoxin-Cyclic GMP Signaling in a Human Enteroid Intestine-Chip Model

Abstract

Modeling host-pathogen interactions with human intestinal epithelia using enteroid monolayers on permeable supports (such as Transwells) represents an alternative to animal studies or use of colon cancer-derived cell lines. However, the static monolayer model does not expose epithelial cells to mechanical forces normally present in the intestine, including luminal flow and serosal blood flow (shear force) or peristaltic forces. To determine the contribution of mechanical forces in the functional response of human small intestine to a virulence factor of a pathogenic intestinal bacterium, human jejunal enteroids were cultured as monolayers in microengineered fluidic-based Organ-Chips (Intestine-Chips) exposed to enterotoxigenic Escherichia coli heat-stable enterotoxin A (ST) and evaluated under conditions of static fluid, apical and basolateral flow, and flow plus repetitive stretch. Application of flow increased epithelial cell height and apical and basolateral secretion of cyclic GMP (cGMP) under baseline, unstimulated conditions. Addition of ST under flow conditions increased apical and basolateral secretion of cGMP relative to the level under static conditions but did not enhance intracellular cGMP accumulation. Cyclic stretch did not have any significant effect beyond that contributed by flow. This study demonstrates that fluid flow application initiates changes in intestinal epithelial cell characteristics relative to those of static culture conditions under both baseline conditions and with exposure to ST enterotoxin and suggests that further investigations of the application of these mechanical forces will provide insights into physiology and pathophysiology that more closely resemble intact intestine than study under static conditions.

Three-Dimensional Regeneration of Patient-Derived Intestinal Organoid Epithelium in a Physiodynamic Mucosal Interface-on-a-Chip

“…Furthermore, the enclosed lumen in an organoid body considerably hampers access to the lumen, by which the co-culture with gut microbiome or the simulation of drug administration is extremely challenging. Thus, this limitation led to the innovation of an “opened” version of an organoid, where the recreation of a mucosal tissue interface of intestinal organoids has been emerged [ 6 , 48 , 49 ]. On top of the previous reports [ 20 , 50 ], we propose an advanced 3D convoluted microdevice that can manipulate multiaxial deformations and independently controlled fluid hydrodynamics in the mucosal interface.…”

“…There have been a number of in vitro human intestine models [ 4 , 5 , 6 , 7 , 8 , 9 ], where the human gut-on-a-chip has shown innovative features to simulate physiological biomechanics [ 10 ], three-dimensional (3D) epithelial morphogenesis [ 11 , 12 ], host–microbiome ecosystem [ 10 , 13 ], anoxic–oxic interface (AOI) [ 14 ], epithelial barrier function, and inflammatory immune responses [ 15 , 16 ]. The implementability of the gut-on-a-chip has been improved by integrating human intestinal organoids that reflect the patient’s genetic heritage [ 17 , 18 ], disease pathophysiology [ 19 ], and host–gut microbiome interactions [ 20 ].…”

Human Microphysiological Models of Intestinal Tissue and Gut Microbiome

“…Evaluation of differential stimuli on the luminal and basal sides of the cells was capable on organ chips but not in conventional cell culture, making organ chips a powerful tool for understanding morphogenesis and development. This was further confirmed in a paper by Sunuwar and colleagues which used human jejunal enteroids to show that luminal and basolateral flow produce a model of continual differentiation and NaCl absorption that mimics normal intestine that will be useful in modeling normal intestinal physiology (Sunuwar et al, 2020).…”

Refining Host-Pathogen Interactions: Organ-on-Chip Side of the Coin

“…Sunuwar et al utilized an intestine chip comprised of human jejunal enteroids in order to assess the effects of flow and repetitive stretch on the secretion of cyclic GMP (cGMP) in response to ETEC heat-stable enterotoxin A (ST). In this study, the authors were able to show, for the first time, that luminal flow and serosal blood flow both enhance secretion of cGMP upon ST exposure, which ultimately leads to intestinal fluid and electrolyte loss [ 39 ].…”