Understanding the roles of distinct fibroblast subpopulations in skin homeostasis and disease

AE1: Molecular and cellular dermatology AE2: Dermal fibroblast biology AE3: Mouse models of skin inflammation and carcinogenesis (DMBA/TPA)

Our goal is to understand how fibroblast heterogeneity contributes to pathological dermal changes. To do this we will characterise fibroblast lineages in adult mouse skin (aim 1); and discover how they contribute to injury-induced skin fibrosis (aim 2), to acute and chronic skin inflammation, and skin tumour development (aim 3). In aim 4 we will translate the findings from mouse models to human skin by identifying human fibroblast subpopulations and assaying their functions in vitro and in vivo.

The underpinning methodology for aims 1-3 is using Tamoxifen-inducible Cre recombinase to express fluorescent reporters of different fibroblast subsets. The location and properties of the fibroblasts will be evaluated by confocal microscopy of histological sections, whole mounts and flat mounts and by flow cytometry of isolated cells. The model of injury-induced fibrosis (aim 2) is application of Bleomycin via an osmotic mini-pump. To study inflammation and development of benign and malignant skin tumours we will use 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) skin carcinogenesis (aim 3). In aim 4 we will filter gene expression profiles of human fibroblasts from different dermal layers against mouse datasets to identify candidate human subpopulations and validate them by antibody labelling of healthy and pathological human skin. Using flow cytometry to isolate human fibroblast subpopulations, we will examine their properties in culture, including immunomodulation, proliferation, alphaSMA expression and ECM production. We will also model human fibroblast dynamics in vivo during skin reconstitution and in grafts of fibrotic skin on NOD/scid/IL-2Rgamma-/- mice. In Aims 2-4 we will attempt to alter connective tissue by selective killing or expansion of fibroblasts of interest. The research has the potential to identify new therapeutic strategies to treat fibrosis and prevent tumour spread.

The proposed research has the potential to benefit many different people. Fibrosis, the topic under investigation, is estimated to contribute to 45% of deaths in the Western world. In the long term our results have the potential to identify new routes to preventing or reversing fibrosis and thus alleviate considerable suffering. The fibrotic characteristics of solid tumours are known to promote tumour aggressiveness and so our studies can also contribute to new anti-cancer treatments.

In the short term, staff employed on the grant will benefit by learning new laboratory skills and expanding international knowledge of an important and exciting research area. Their productivity will give them career progression and by the end of the grant the postdoctoral researchers will be equipped to run their own laboratories. Their expertise in presenting work both in writing and orally can also be applied to many other employment sectors.

The wider academic and clinical research community will benefit from the research since our elucidation of fibroblast heterogeneity will lead to new concepts of injury- and cancer-associated fibrosis that will stimulate avenues of research. Their research will be facilitated by the data, experimental tools and protocols that we generate. The research will benefit the commercial sector through partnerships to develop new drugs and biologics to treat disease.

The public will benefit from the research through our outreach activities, which will increase their knowledge of fibrosis and stimulate their enthusiasm for research. By presenting our work to school children and through cultural events we will not only increase public understanding of science but promote interchange between the arts and sciences.

Our work will benefit the UK government, Pharma and the wider public by growing next generation researchers, providing fundamental insights into disease mechanisms, and exploiting those insights to improve patient care.