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

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.

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).