Postovulatory ovarian repair: a role for LOX in scar-free adult healing

Lead Research Organisation: University of Edinburgh
Department Name: Edinburgh Research and Innovation

Abstract

Each month the surface lining of the ovary (ovarian surface epithelium, OSE) is injured when the egg is released (ovulation) and then heals without a scar. In contrast the adjacent surface lining of the pelvic cavity (peritoneal surface epithelium, PSE) if injured, for example during surgery or infection, often heals with scarring (adhesion formation). Peritoneal adhesions are a major cause of severe pelvic pain, infertility, reduced quality of life, re-admission for additional surgery and potentially life-threatening bowel obstruction. The impact on an individual?s health and healthcare costs is thus considerable. In our proposed research, we ask: how is the ovary protected from scarring? and, how can this knowledge be applied to treat or prevent peritoneal adhesions?
We know that the absence or presence of scarring is determined within the cell itself. This may be by the cell switching on or switching off substances known as, steroids and retinoids that in turn influence whether or not a cascade of events is set in motion to form a scar. A key substance we propose to study is an enzyme called LOX (lysyl oxidase), that we believe plays a central role in scar formation.
We propose to use modern molecular and cellular research techniques to inform us about the role for LOX in scar-free healing in an animal (mouse) model and then translate our findings to human cells in tissue culture outside the body.
Our proposal combines the expertise, knowledge and skills of clinical and basic scientists in order to ensure the results of our research are relevant and translatable to the clinical problem(s) of adhesion formation ?at the bedside?. Additionally, this knowledge has potential to help develop approaches to minimise scar formation during human wound healing at large.

Technical Summary

We propose a novel transdisciplinary approach to unravel cellular mechanisms responsible for peritoneal adhesions in women that cause extreme pelvic pain, infertility and potentially lethal bowel obstruction. The experimental approach relies on the fact that injury or even transient inflammation of the peritoneal surface epithelium (PSE) leads to healing with fibrosis (scarring), whereas the ovarian surface epithelium (OSE) is regularly subjected to ovulation-associated injury that heals without fibrosis. The OSE represents a unique human model of scar-free adult wound healing. We have evidence that the anti-inflammatory and anti-fibrogenic machinery in human OSE and PSE cells differ based on intracrine (in)activation of steroid and retinoid signals that affect inflammation and fibrosis. We aim to dissect the molecular and cellular basis for these differences as a platform for new diagnostic and treatment modalities for inflammatory and fibrotic gynaecological pathologies linked to ovulation (pelvic adhesions, endometriosis). We present strong preliminary data to support a determinant role for lysyl oxidase (LOX) in peritoneal scarring. LOX is an amine-oxidase enzyme essential for the cross-linking of fibroblast-derived collagens and deposition of insoluble collagen fibres that are major structural component of fibrotic tissues. Intracrine stimuli (steroids, retinoids) regulate LOX expression in response to the local milieu. Our guiding hypothesis is that suppression of fibre deposition and cross-linkage via LOX expression and enzymatic activity is critical to scar-free healing. We have strong proof of concept in vivo from a murine model that inhibition of LOX activity suppresses peritoneal fibrosis. We now aim to: (1) Confirm and define a central role for LOX in fibrosis and scarring and; to answer (2) Do ovarian steroids and retinoids minimise fibrosis by suppression of LOX in OSE cells; (3) Is peritoneal fibrosis due to deficient intracrine suppression of LOX?
We will investigate the role of LOX in a model of experimentally induced peritoneal fibrosis in vivo and in vitro. The murine in vivo model is based on intra-peritoneal. injection of carbon nanotubes to generate inflammation and formation of granulomata. Local access to 11betaHSD1-/- mice in which to explore the contribution of locally generated (intracrine) cortisol to modulation of peritoneal fibrosis considerably enhances the power of this model. Proposed in vitro studies with primary human OSE and PSE cells provide a critical translational component.
Our results will impact the design of improved approaches to the treatment of peritoneal adhesions, endometriosis, and fibrotic pathologies in other parts of the body (liver, lung).

Publications

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Hillier SG (2013) IVF endocrinology: the Edwards era. in Molecular human reproduction

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Hillier SG (2012) Nonovarian origins of ovarian cancer. in Proceedings of the National Academy of Sciences of the United States of America

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Iredale JP (2016) BREXIT and science, where do we go from here. in QJM : monthly journal of the Association of Physicians

 
Description Generation of conditional Floxed Lysyl Oxidase mouse 
Organisation University of Oulu
Department Biocenter Oulu
Country Finland 
Sector Academic/University 
PI Contribution We are visiting our collaborators to give a seminar about our current research project and to discuss progress in the generation 0f the Knockout mouse
Collaborator Contribution Prof Johanna Myllyharju and Dr Joni Maku are developing the Floxed Lysyl oxidase mouse that we will make use of in our research to test the critical role of Lysyl Oxidsa in peritoneal fibrosis and adhesions.
Impact This collaboration will enable us to study, for the first time, the specific role of LOX in the peritoneal mesothelium using an in vivo model.
Start Year 2010
 
Description Surgical model of peritoneal fibrosis 
Organisation University of Manchester
Department School of Medicine Manchester
Country United Kingdom 
Sector Academic/University 
PI Contribution We have initiated discussions about different models of peritoneal fibrosis and discussed our current in vivo and in vitro models with Dr Herrick
Collaborator Contribution Collaboration with Dr Sarah Herrick has enabled us to develop a surgical model of peritoneal fibrosis. making use of the expertise of Dr Herrick in this area.
Impact This collaboration will enable us to further test our hypothesis that regulation of Lysyl Oxidase is central to the formation of peritoneal adhesions and fibrosis.
Start Year 2011