• Expert ANR

• Direction d'équipe

• Sciences du Vivant
  
• Physique/Physique/Biophysique
  
• Physique/Matière Condensée/Mécanique statistique
  
• Physique/Matière Condensée/Matière Molle
  
• Sciences du Vivant/Ecologie, Environnement/Santé
  
• Sciences du Vivant/Biotechnologies
  
• Sciences de l'ingénieur/Génie des procédés
  
• Sciences de l'ingénieur/Milieux fluides et réactifs
  
• Chimie/Polymères
  
• Chimie/Matériaux
  
• Physique/Matière Condensée/Science des matériaux
  
• Physique/Mécanique/Mécanique des solides
  
• Chimie/Chimie organique
  
• Physique/Matière Condensée/Autre
  

The airway epithelium represents a fragile environmental interface potentially disturbed by cigarette smoke, the major risk factor for developing Chronic Obstructive Pulmonary Disease (COPD). Cigarette smoke leads to bronchial epithelial damage on ciliated, goblet and club cells, which could involve calcium signaling. Calcium is a key messenger involved in virtually all fundamental physiological functions, including mucus and cytokine secretion, cilia beating and epithelial repair. In this study, we analyzed calcium signaling in Air-Liquid Interface reconstituted bronchial epithelium from control subjects and smokers (with and without COPD). We further aimed to determine how smoking impaired calcium signaling. Firstly, we showed that the endoplasmic reticulum (ER) depletion of calcium stores was decreased in COPD patients and that the calcium influx was decreased in epithelial cells from smokers (regardless of COPD status). In addition, acute cigarette smoke exposition lead to a decrease in ER calcium release, significant in smoker subjects, and to a decrease in calcium influx only in control subjects. Furthermore, the differential expression of 55 genes involved in calcium signaling highlighted that only ORAI3 expression was significantly altered in smokers (regardless of COPD status). Finally, we incubated epithelial cells with an ORAI antagonist (GSK-7975A). GSK-7975A altered calcium influx and ciliary beating but not mucus and cytokine secretion or epithelial repair in control subjects. Our data suggest that calcium signaling is impaired in smoker epithelia (regardless of COPD status) and involves ORAI3. Moreover, ORAI3 is additionally involved in ciliary beating.

The mucociliary function of the bronchial epithelium ensures the continuous clearance of the respiratory system. This function relies on two main elements: mucus properties and cilia beating coordination. We work on high speed optical microscopy videos of Human bronchial epithelium from ALI (Air-liquid interface) cultures. We present here a technique based on the tracking of each cilium and on the spatiotemporal analysis of the obtained trajectories. To relate each cilium to its corresponding cell, a clustering method is used. The spatiotemporal coordination can than be quantified both, inside and in-between ciliated cells. In addition the physical parameters can be mapped to observe the heterogeneity of the cilia activity and compare different pathologies.

We describe an original method to measure mucus microrheology on human bronchial epithelium culture using optical tweezers. We probed rheology on the whole thickness of mucus above the epithelium and showed that mucus gradually varies in rheological response, from an elastic behavior close to the epithelium to a viscous one far away. Microrheology was also performed on mucus collected on the culture, on ex vivo mucus collected by bronchoscopy, and on another epithelium model. Differences are discussed and are related to mucus heterogeneity, adhesiveness and collection method.

The mucociliary function of the bronchial epithelium ensures the continuous clearance of the respiratory system, which relies on two main elements: mucus and cilia beating coordination.We perform here a rheological characterization of mucus samples extracted from ALI (Air-liquid interface) cultures of bronchial epithelium. Our approach combines macro- and micro-rheology techniques with the aim of quantifying the mucus viscoelastic properties at different length scales (from the size of bronchial cilia up to the scale on which mucus is transported). This specific methodology allows us to compare samples corresponding to different patient pathologies.In addition, we will describe our method to quantitatively characterize the coordination between cilia and how density and spatial distribution influences this coordination and consequently the mucus motion, required for the mucoliary clearance.

The bronchial epithelium mucociliary function ensuring the lung continuous clearance relies on mucus rheological properties and cilia beating coordination. We focus on two points: first, the biochemical and physical parameters affecting the mucus viscoelastic properties; secondly, the cilia coordination and its coupling with the mucus.We performed rheological experiments on mucus extracted from Air Liquid Interface cultures of bronchial epithelium reconstituted from bronchial biopsies. We combine standard macro-rheology to micro-rheology performed with optical tweezers, to quantify the mucus flowing behaviour at two scales: the mucus layer thickness and the cilia or bacteria scale. Macro- and micro-rheology give different results: an elastic plateau (1-2 Pa) at the macro-scale; a viscous flow (10-3-10-2 Pa) at the micro-scale but with an important adhesion and elasticity at the interfaces. We also perform original experiments using optical tweezers directly on the epithelium, to access the viscoelastic response in the various mucus layers. We obtain an increased elasticity in the vicinity to the epithelium.Finally, the study of the physical mucus properties coupled with the specific methodology we developed to quantify cilia activity, coordination and mucus velocity field, should help to evaluate the efficiency of the mucociliary function and to understand the mechanisms of clearance.