A rat, dog, and human Liver-Chip designed using microengineered Organs-on-Chips technology recapitulates species-specific drug toxicities.

We show that mucociliary membranes of animal epithelia can create fluid-mechanical microenvironments for the active recruitment of the specific microbiome of the host. In terrestrial vertebrates, these tissues are typically colonized by complex consortia and are inaccessible to observation. Such tissues can be directly examined in aquatic animals, providing valuable opportunities for the analysis of mucociliary activity in relation to bacteria recruitment. Using the squid–vibrio model system, we provide a characterization of the initial engagement of microbial symbionts along ciliated tissues. Specifically, we developed an empirical and theoretical framework to conduct a census of ciliated cell types, create structural maps, and resolve the spatiotemporal flow dynamics. Our multiscale analyses revealed two distinct, highly organized populations of cilia on the host tissues. An array of long cilia ( <mml:math><mml:mo>∼</mml:mo></mml:math>∼ 25 <mml:math><mml:mi mathvariant="normal">μ</mml:mi></mml:math>μ m) with metachronal beat creates a flow that focuses bacteria-sized particles, at the exclusion of larger particles, into sheltered zones; there, a field of randomly beating short cilia ( <mml:math><mml:mo>∼</mml:mo></mml:math>∼ 10 <mml:math><mml:mi mathvariant="normal">μ</mml:mi></mml:math>μ m) mixes the local fluid environment, which contains host biochemical signals known to prime symbionts for colonization. This cilia-mediated process represents a previously unrecognized mechanism for symbiont recruitment. Each mucociliary surface that recruits a microbiome such as the case described here is likely to have system-specific features. However, all mucociliary surfaces are subject to the same physical and biological constraints that are imposed by the fluid environment and the evolutionary conserved structure of cilia. As such, our study promises to provide insight into universal mechanisms that drive the recruitment of symbiotic partners.

We use a three-dimensional computational model to study the fluid transport and mixing due to the beating of an infinite array of cilia. In accord with recent experiments, we observe two distinct regions: a fluid transport region above the cilia and a fluid mixing region below the cilia tip. The metachronal wave due to phase differences between neighbouring cilia is known to enhance the fluid transport above the ciliary tip. In this work, we show that the metachronal wave also enhances the mixing rates in the sub-ciliary region, often simultaneously with the flow rate enhancement. Our results suggest that this simultaneous enhancement in transport and mixing is due to an enhancement in shear flow. As the flow above the cilia increases, the shear rate in the fluid increases and this shear enhances stretching, which is an essential ingredient for mixing. Estimates of the mixing time scale indicate that, compared to diffusion, the mixing due to the cilia beat may be significant and sometimes dominates chemical diffusion.

Viral-induced exacerbation of asthma remains a major cause of hospitalization and mortality. New human-relevant models of the airways are urgently needed to understand how respiratory infections may trigger asthma attacks and to advance treatment development. Here, we describe a new human-relevant model of rhinovirus-induced asthma exacerbation that recapitulates viral infection of asthmatic airway epithelium and neutrophil transepithelial migration, and enables evaluation of immunomodulatory therapy. Specifically, a microengineered model of fully differentiated human mucociliary airway epithelium was stimulated with IL-13 to induce a T-helper cell type 2 asthmatic phenotype and infected with live human rhinovirus 16 (HRV16) to reproduce key features of viral-induced asthma exacerbation. We observed that the infection with HRV16 replicated key hallmarks of the cytopathology and inflammatory responses observed in human airways. Generation of a T-helper cell type 2 microenvironment through exogenous IL-13 stimulation induced features of asthmatic airways, including goblet cell hyperplasia, reduction of cilia beating frequency, and endothelial activation, but did not alter rhinovirus infectivity or replication. High-resolution kinetic analysis of secreted inflammatory markers revealed that IL-13 treatment altered IL-6, IFN-λ1, and CXCL10 secretion in response to HRV16. Neutrophil transepithelial migration was greatest when viral infection was combined with IL-13 treatment, whereas treatment with MK-7123, a CXCR2 antagonist, reduced neutrophil diapedesis in all conditions. In conclusion, our microengineered Airway Lung-Chip provides a novel human-relevant platform for exploring the complex mechanisms underlying viral-induced asthma exacerbation. Our data suggest that IL-13 may impair the hosts’ ability to mount an appropriate and coordinated immune response to rhinovirus infection. We also show that the Airway Lung-Chip can be used to assess the efficacy of modulators of the immune response.