Mice exhibitingIn Vivo Micro-CT Assessment of Airway Remodelingboth inflammation and remodeling, which is consistent with our previous study [16]. Such a result can be explained by the fact that the region of interest of the PBA encompassed lung Acetovanillone parenchyma Microcystin-LR web beyond the bronchial wall, thereby including inflammatory cells located outside the bronchial wall (Figs. 3A and 3B). Indeed, in mice as well as in humans, remodeling is only located within the bronchial wall whereas inflammation occurs not only in bronchi but also in the distal lung parenchyma [17,31]. Therefore, the normalization by the whole lung attenuation might have withdrawn inflammation from the PBA value. Our results suggest that micro-CT could be considered for monitoring remodeling when testing new drugs targeting remodeling in longitudinal studies. Micro-CT could also be used as a complement of histology since our technique allows a threedimensional and comprehensive assessment of remodeling, while histology only provides two-dimensional information from small samples. The 3D semi-automatic method, we validated here, is less time-consuming (8 min vs. 40 min) than the manual method [16] since it requires no manual drawing. Of note, micro-CT examinations were performed after endotracheal intubation. Intubating a mouse is a subtle technique requiring a training phase and may induce injury if improperly done. Free-breathing techniques have been developed to avoid intubation [32,33], however they cannot reach the same quality of gating than those under mechanical ventilation. To avoid any confounding effect related to repeated anaesthesia, tracheal intubation, or radiation exposure, we did not study a unique cohort of mice at threedifferent time points. Likewise, age-matched control mice were necessary to avoid potential confounding effects due to age-related changes. Potential applications in humans are also conceivable. Even if molecular imaging is thought to play a crucial role in a near future by targeting specific proteins or receptors involved in asthma [34], multidetector CT might be an easier cost-effective tool, and is immediately available. In COPD patients, bronchial wall attenuation has been recently shown to be increased as compared to control subjects, and significantly correlated to functional obstructive parameters [35?7]. Thus, the peribronchial attenuation might be considered as a potential translational concept. Our results in mice should open the way to further studies in humans, aimed at identifying CT markers of asthma. To conclude, a non-invasive assessment of bronchial remodeling in asthmatic mice is feasible using in vivo respiratory-gated micro-CT. The peribronchial attenuation value normalized by the total lung attenuation value appears to be the most reliable marker of remodeling. It may help evaluate new drugs targeting airway remodeling in pre-clinical and clinical studies.Author ContributionsConceived and designed the experiments: ML PB. Performed the experiments: ML AO GD OO POG HB. Analyzed the data: ML AO GD POG HB MM FL PB. Contributed reagents/materials/analysis tools: ML GD RM PB. Wrote the paper: ML RM PB.
The smallpox eradication campaign, which was promoted by the World Health Organization (WHO) in the 1960s and 1970s, represents a major milestone in medical history [1,2]. After centuries of epidemics and deaths, smallpox was declared eradicated in 1980. The etiological agent of smallpox is the Variola virus (VARV), a member of the Poxvir.Mice exhibitingIn Vivo Micro-CT Assessment of Airway Remodelingboth inflammation and remodeling, which is consistent with our previous study [16]. Such a result can be explained by the fact that the region of interest of the PBA encompassed lung parenchyma beyond the bronchial wall, thereby including inflammatory cells located outside the bronchial wall (Figs. 3A and 3B). Indeed, in mice as well as in humans, remodeling is only located within the bronchial wall whereas inflammation occurs not only in bronchi but also in the distal lung parenchyma [17,31]. Therefore, the normalization by the whole lung attenuation might have withdrawn inflammation from the PBA value. Our results suggest that micro-CT could be considered for monitoring remodeling when testing new drugs targeting remodeling in longitudinal studies. Micro-CT could also be used as a complement of histology since our technique allows a threedimensional and comprehensive assessment of remodeling, while histology only provides two-dimensional information from small samples. The 3D semi-automatic method, we validated here, is less time-consuming (8 min vs. 40 min) than the manual method [16] since it requires no manual drawing. Of note, micro-CT examinations were performed after endotracheal intubation. Intubating a mouse is a subtle technique requiring a training phase and may induce injury if improperly done. Free-breathing techniques have been developed to avoid intubation [32,33], however they cannot reach the same quality of gating than those under mechanical ventilation. To avoid any confounding effect related to repeated anaesthesia, tracheal intubation, or radiation exposure, we did not study a unique cohort of mice at threedifferent time points. Likewise, age-matched control mice were necessary to avoid potential confounding effects due to age-related changes. Potential applications in humans are also conceivable. Even if molecular imaging is thought to play a crucial role in a near future by targeting specific proteins or receptors involved in asthma [34], multidetector CT might be an easier cost-effective tool, and is immediately available. In COPD patients, bronchial wall attenuation has been recently shown to be increased as compared to control subjects, and significantly correlated to functional obstructive parameters [35?7]. Thus, the peribronchial attenuation might be considered as a potential translational concept. Our results in mice should open the way to further studies in humans, aimed at identifying CT markers of asthma. To conclude, a non-invasive assessment of bronchial remodeling in asthmatic mice is feasible using in vivo respiratory-gated micro-CT. The peribronchial attenuation value normalized by the total lung attenuation value appears to be the most reliable marker of remodeling. It may help evaluate new drugs targeting airway remodeling in pre-clinical and clinical studies.Author ContributionsConceived and designed the experiments: ML PB. Performed the experiments: ML AO GD OO POG HB. Analyzed the data: ML AO GD POG HB MM FL PB. Contributed reagents/materials/analysis tools: ML GD RM PB. Wrote the paper: ML RM PB.
The smallpox eradication campaign, which was promoted by the World Health Organization (WHO) in the 1960s and 1970s, represents a major milestone in medical history [1,2]. After centuries of epidemics and deaths, smallpox was declared eradicated in 1980. The etiological agent of smallpox is the Variola virus (VARV), a member of the Poxvir.