Development of an Immune Competent In Vitro Skin Equivalent to Investigate the Impact of Air Pollution on Skin Health

Abstract

The impact of air pollution on skin health remains an understudied topic but there is mounting evidence to suggest it can cause damage to the structure and function of the tissue. Critical to understanding this impact is the generation of in vitro skin equivalent models that can accurately recapitulate the complex anatomy of the in vivo tissue. In this thesis, we have bioengineered a novel immune competent full thickness skin equivalent that contains functional Langerhans cells These skin equivalents have been utilised to investigate the effect of pollution on the inflammatory responses of the skin.
We have successfully developed a system to apply particulate matter, one of the main components of air pollution, to the surface of skin equivalent models that does not in itself damage the tissue. We have demonstrated though in depth ultrastructural analysis that particulate matter adheres to the surface of the stratum corneum, but significantly showed that the particles do not penetrate deeper into the tissue.
Many previous studies have utilised two dimensional monolayer cultures or simple epidermal models to investigate the deleterious effects of air pollution on skin. In this project we have developed an immune-competent full thickness skin equivalent model that contains an Alvetex® Scaffold based dermis that contains human fibroblast that secrete endogenous extracellular matrix proteins and a stratified epidermis containing MUTZ-3 cell line derived Langerhans cells. We subsequently demonstrated that these Langerhans cell containing skin models show a greater increase in pro-inflammatory cytokine production in response to known allergens and irritants. Thus, we have shown that these cell line derived Langerhans cells behave like their in vivo counterparts.
Skin equivalent models exposed to particulate matter showed an increase in pro-inflammatory mediator production which suggest that even without the particulate physically penetrating the epidermal barrier these pollutants can still initiate deleterious responses. Additionally, full thickness models containing Langerhans cells showed a greater inflammatory response to particulate matter than the non-immune-competent skin equivalents. Overall, this demonstrates the involvement of the skin’s immune system in responding to air pollution exposure.