A Stiff Extracellular Matrix Favors the Mechanical Cell Competition that Leads to Extrusion of Bacterially-Infected Epithelial Cells

Abstract

Cell competition refers to the mechanism whereby less fit cells (“losers”) are sensed and eliminated by more fit neighboring cells (“winners”) and arises during many processes including intracellular bacterial infection. Extracellular matrix (ECM) stiffness can regulate important cellular functions, such as motility, by modulating the physical forces that cells transduce and could thus modulate the output of cellular competitions. Herein, we employ a computational model to investigate the previously overlooked role of ECM stiffness in modulating the forceful extrusion of infected “loser” cells by uninfected “winner” cells. We find that increasing ECM stiffness promotes the collective squeezing and subsequent extrusion of infected cells due to differential cell displacements and cellular force generation. Moreover, we discover that an increase in the ratio of uninfected to infected cell stiffness as well as a smaller infection focus size, independently promote squeezing of infected cells, and this phenomenon is more prominent on stiffer compared to softer matrices. Our experimental findings validate the computational predictions by demonstrating increased collective cell extrusion on stiff matrices and glass as opposed to softer matrices, which is associated with decreased bacterial spread in the basal cell monolayer in vitro. Collectively, our results suggest that ECM stiffness plays a major role in modulating the competition between infected and uninfected cells, with stiffer matrices promoting this battle through differential modulation of cell mechanics between the two cell populations.

Spatiotemporal characterization of endothelial cell motility and physical forces during exposure to Borrelia burgdorferi

“… Save the strain energy overtime as a .mat file and input to Prism if you wish to do statistical analysis of various independent experiments (see troubleshooting 5 ) ( Figure 5 B). Based on the calculated traction stresses you can infer also monolayer stresses built within the cellular monolayer using MSM 16 ( Figures 6 A and 6B). Note: For our custom-built scripts in MATLAB (MathWorks) please refer to: https://github.com/ebastoun/Monolayer-Stress-Microscopy .…”

“…Based on the calculated traction stresses you can infer also monolayer stresses built within the cellular monolayer using MSM 16 ( Figures 6 A and 6B). Note: For our custom-built scripts in MATLAB (MathWorks) please refer to: https://github.com/ebastoun/Monolayer-Stress-Microscopy .…”

“… 2 , 3 , 4 The codes for MSM are uploaded in our gitlab repository together with instructions on how to run them https://github.com/ebastoun/Monolayer-Stress-Microscopy . 16 Statistical parameters and significance are reported in the corresponding Figures and the Figure Legends. Boxplots and plots represent mean+/-SEM as indicated.…”

Mechanosensory feedback loops during chronic inflammation

“…In addition to elastic stiffness of tissues and cellular substrates, viscoelastic properties of ECM networks also influence coordinated cell movements. Crosslinking of collagen networks leads to increased network stiffness and reduces viscoelasticity, resulting in reduced collective migration (Murrell et al, 2011;Clark et al, 2022). Interestingly, changes in tissue viscoelasticity have also recently been shown to regulate collective cell behavior during development and cell invasion (Barriga and Mayor, 2019;Elosegui-Artola, 2021;Elosegui-Artola et al, 2023).…”

“…Pathologically stiff tissue can promote immune cell recruitment and activation via mechanosensing pathways, leading to increased immune cell migration and differentiation and activation of fibroblasts ( Chen et al, 2020 ; Atcha et al, 2021 ; Chirivì et al, 2021 ; Jiang et al, 2022 ). Increased tissue stiffness also results in epithelial cell depolarization, reduced cell-cell junctions and increased migration ( Discher et al, 2005 ; Aparicio-Yuste et al, 2022 ). While in the short-term this may aid in wound resealing, epithelial cells on stiff environments are less able to maintain a tight barrier, creating a feedback loop between increased barrier permeability and inflammation mediated by changes in tissue mechanics ( Figure 1 ).…”