Influence of chemical and mechanical stress on precision-cut lung slices

Lungs are exposed to different forms of stress such as chemical substances, allergens or in the form of direct tissue injury. This study examined whether precision-cut lung slices are suitable as a model for studying different types of stress. We established the use of PCLS from sheep to study the response of airways and vessels to mediators. According to in vivo experiments sheep are thought to represent the human pathophysiology better than rodents. We therefore established the use of sheep PCLS and showed that methacholine, serotonin and endothelin-1 lead to a bronchoconstriction, while the response to leukotriene and thromboxane was rather weak. PCLS were also produced from preterm sheep and compared to adult sheep, which revealed a decreased reagibility to methacholine and serotonin in preterm sheep. Comparison of the bronchoconstriction of sheep PCLS with bronchoconstriction data from human PCLS revealed a less satisfactory accordance than the one seen in vivo. Although sheep PCLS may not represent the characteristics of human PCLS completely, the results presented in this thesis indicate that they are closer to human PCLS than PCLS from rodents. Another kind of stress that we examined was chemical stress. This study also aimed at studying the usefulness of PCLS to study respiratory allergens as required in the REACH (Regulation, Evaluation, Authorisation and restriction of CHemicals) process. Bronchoconstriction in PCLS as response to chemical allergen was investigated and compared to bronchoconstriction in vivo. For this purpose a well established sensitisation protocol with TMA, a respiratory allergen and DNCB, a dermal allergen, was used. The early allergic response and airway hyperresponsiveness in mouse PCLS was investigated and compared to data from in vivo invasive measurements. Acquired measurements were comparable suggesting PCLS as a reasonable alternative to invasive lung function measurements. Hence, stress-related bronchoconstriction to chemical allergens may be a suitable predictability for in vivo experiments. Several in vivo and cell culture models have been developed to study the pulmonary responses to mechanical stretch. While providing extremely useful information, these models do also suffer from limitations in being either too complex for detailed mechanical or mechanistic studies, or being devoid of the full complexity present in vivo (e.g. different cell types and interstitial matrix). Therefore, we developed a new model, based on the biaxial stretching of precision-cut lung slices. Single PCLS were mounted on a thin and flexible carrier membrane of PDMS in a bioreactor and the membrane was stretched by applying varying pressures under static conditions. A gene array revealed a general upregulation of immune response and wound healing genes by the slicing process. Stretch markers like amphiregulin were upregulated in PCLS by the slicing process. This upregulation was dependent on tyrosin kinases and the cytoskeleton, but could not be blocked sufficiently, which made it complicated to differentiate a stretch response from the basal increase. Distension of the PCLS was modelled via finite element simulation. According to this analysis, lung tissue was stretched by up to 38% in the latitudinal and by up to 44% in the longitudinal direction resulting in alveolar distension similar to what has been described in intact lungs. Lung slices were stretched dynamically with a frequency of 0.25 Hz for 4h, without causing cell injury. This indicates that the distension of PCLS in the bioreactor may not be suitable to study gene expression but allow the calculation of deformation and occurring forces of the PCLS during the stretching process. PCLS are a suitable model for studying different forms of stress in the lung and allows the investigation of different pathophysiological situations. Additionally, PCLS may serve as a link between different species.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2010

Author dc:creator

• Dassow, Constanze

Contributors dc:contributor

• Uhlig, Stefan

• info:eu-repo/classification/ddc/570
• Lunge
• Lungenverletzung
• Atemwege
• Künstliche Beatmung
• Bronchialasthma
• Dehnung
• Biowissenschaften, Biologie
• PCLS
• Alveolen
• Bronchokonstriktion
• lung stretch
• bronchoconstriction
• alveoli
• species differences

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113927%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A51657