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The characterisation of cellular and tissue chronic inflammation in recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) occurs as a result of loss of function mutations in COL7A1, resulting in reduced/absent collagen VII deposition in the anchoring fibril adhesion structures at the dermal-epidermal junction. The condition is typified by severe trauma-induced blistering and cutaneous erosions from infancy and chronic wounds that progress to early aggressive cutaneous squamous cell carcinomas (SCCs) which are the main cause of death in this patient cohort. Thus far, the RDEB chronic inflammatory environment has not been characterised in detail nor is there any theoretical basis for the targeting of candidate genes or inflammatory biomarkers to reduce chronic inflammation that might halt the inevitable malignant decline. The studies presented herein provide a detailed comparative analysis of RDEB wounded skin and control skin at the transcriptional and immunological levels. The findings presented in this thesis: 1) define baseline gene expression profiles and immunobiology of chronically inflamed RDEB skin and blood; 2) reveal matrix metalloproteinase (MMP) family genes germane to RDEB chronic inflammation; 3) provide a body of data and supportive evidence that targeting interleukin (IL)-17-associated signalling pathways may be therapeutically meaningful for treating RDEB patients with chronic wounds; and 4) generate new insights into the functional relevance of these targets in RDEB wounds and RDEB-SCC. Illumina whole-genome expression microarray was used to define the pattern of differential gene expression in RDEB wounded skin. MMP-11, -2 and -9 were revealed as significantly upregulated in RDEB chronic wounds, with augmented MMP-11 levels disclosed in the sera of an extended RDEB cohort. Detailed immunoprofiling of RDEB skin and blood via fluorescence-activated flow cytometry revealed a significant elevation in the pro-inflammatory and pro-tumourigenic cytokine IL-17A, further supported on serum multiplex analyses and correlating with immunohistochemical labelling of RDEB wound and RDEB-SCC cutaneous sections. IL-17A significantly enhanced RDEB and RDEB-SCC fibroblast migration and MMP inhibition alone was insufficient to inhibit this effect. An in vitro organotypic model system was developed to study the effects of IL-17A and MMP-11 on RDEB keratinocytes, although pre-treatment did not induce keratinocyte migration or curtail cell invasion in the RDEB-SCC co-cultures. Taken together, these data provide rationale for future work to examine the potential utility of anti-IL-17 biologic innovations as a therapy for individuals with RDEB, although more detailed functional pre-clinical studies are still needed.
Date January 2015
CreatorsProudfoot, Laura Erin
ContributorsMcGrath, John Alexander ; Nestle, Frank Oliver
PublisherKing's College London (University of London)
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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