RORgamma+ Innate Lymphoid Cells in Skin Wound Healing

Normal wound healing is continually occurring in the body and has a key role in maintaining normal health and fitness. Recently it has been shown in the intestine that a specialised type of immune cells called innate lymphoid cells have a key role in maintaining normal gut function. We have found that these cells can travel to the skin have a key role in the normal healing of cuts and abrasions. This occurs through preventing the "adaptive" immune cells, T lymphocytes from causing the induction of scar like tissue in wounds. When normal healing fails to occur properly it can induce painful and difficult to treat pathologies, thus the need to better understand the process of normal wound healing. In this research proposal we will analyse the signals that orchestrate the normal healing process and how these are regulated so wounds heal quickly without leaving disfiguration. We will determine how immune cells are recruited to the wound sites and what happens to them when wounds are fully healed. We will analyse how the different cells communicate with each other and how the timing of these signals controls the normal healing process. We will investigate how this process can be modulated by the presence of opportunistic bacteria that can infect wounds and how this changes the wound healing process. Through working with clinical samples and industrial collaborators we will work towards translating the results of this research into the clinic.

Conventionally the immune system is portrayed as an army of soldiers ready to destroy invading bacteria and viruses. Our preliminary data suggest that a subset of immune cells should be seen as "healers" rather than "soldiers", with a special role in maintaining normal wound healing. Through understanding how the immune cells controls the function and repair of the skin barrier will help in the development of new treatments for inflammatory skin disorders and ulcerative lesions, major unmet medical challenges.

We have recently discovered a uniqure role for Notch signalling in epithelial cells driving the recruitment and function of innate lymphoid cells during normal wound healing. Notch1 and Notch2 signalling regulate different steps in the wound healing process; Notch2/jagged1 signalling induces TNF alpha production leading to CCL20 and subsequent recruitment of innate lymphoid cell (ILC) to the wound site. Subsequent Notch1 signalling in epithelial cells induces IL-23 production at the wound site activating ILCs and driving IL-22 expression. One of the key roles of innate lymphoid cells appears to be preventing T cell mediated pathology in wound sites. Thus Innate Lymphoid Cells have an unexpected role as regulators of wound pathology at mucosal surfaces thus we will address the following questions:

1) How do ILCs regulate pathology from forming during normal healing, in particular is this process dependent on the amount and timing of cytokine production?

2) The cytokines IL22 and IL23 are produced at the wound sites, which cells produce these cytokines and what is their functional relevence to wound closure?

3) Infections are commonly associated with wounds, what role does infection have in the production of different cytokines at the wound site and in particular why is the cytokine IL17 not found in normal wound healing?

4) How is the dynamics of immune cell entry and clearance from the wound microenvironment occur?

Through combining genetic mouse models with functional assays, gene expression analysis and multi-photon imaging we will determine molecular mechanism of immune mediate regulation of normal wound healing in both mouse models and human disease.

The skin is the waterproof barrier that protects the body from infections through preventing pathogen entry. Wound complications cost the NHS over £3 billion/year. Inflammatory skin conditions are massive burden on the health system and have social impacts through extended nursing, work absences and psychological impacts. Research into normal skin repair will provide insights into how wound pathologies develop, potentially leading to novel treatments for ulcerative lesions and wound scarring. Immune cell infiltration has key roles in normal wound healing process and pathology formation. In this grant we will focus on the role of a newly identified immune cell population we have found in wounds. Through manipulating the recruitment and function of these cells, we believe it might be possible to prevent and treat wound scarring.

Impact in Immunology: ILCs and IL22 have been shown to have key role in maintaining the intestinal barrier and thymus regeneration. In some inflammatory skin pathologies and IBD, ILC expression of IL17 has a role in disease pathology. Understanding mechanisms of ILC recruitment, cytokine expression and function will impact on understanding their function in other epithelial tissues and mucosal barriers.

Industrial impact: This work is highly likely to be of significant importance for pharmaceutical companies developing drugs for chronic inflammatory diseases and ulcerative wounds. We have already discovered a novel Notch-dependent mechanism for recruiting ILCs to wound sites and we are working with Chris Siebel (Genentech) to further define this pathway. Additionally, we have existing links with Dan Cua (Merck) and Jonathan Sherlock (Birmingham) who are interested in understanding how IL22/Il23 regulating ILCs in wound healing. This is of particular importance as stage 1 clinical trials using anti-IL23 antibodies were exceptionally effective in treating human psoriasis. Thus a better understanding of IL23s in maintaining normal skin barrier function is important. Additionally our preliminary data shows that cytokine deliver into wound sites can accelerate wound healing, thus it is be possible to fine tune the wound healing process using biologics. Furthermore, an outcome of this project is a mechanistic understanding of why ILCs express ILC22 or ILC17 in skin wounds. Given the importance of IL 17 producing cells in skin pathologies novel therapeutic targets may be identified. We have appropriate MTA and knowledge transfer agreements in place for the respective industrial partners and data generated outside these agreements will be protected by patents at Durham and York Universities. We have additional links with UK Pharmaceutical companies; MC has 2 PhD students CASE funded by GSK, 1 postdoc with Medimmune (Cambridge) and has previously had 2 CASE PhD students with AstraZeneca. MC and CA have currently working with Unilever on skin imaging and immunology. Through working with industry and maintaining close contacts with the pharmaceutical industry we aim to increase the impact of the research and translate the outcomes into new therapeutics.

Bench to Bedside: There is no current understanding of the role of ILCs in chronic wounds. It is likely that as an outcome of this grant new treatment regimes may be devised using currently approved medications. AB has had extensive success applying primary research to improve treatments for chronic wounds patients, leading to dramatic resolution of previously untreatable leg ulcers. Through combining in vivo mouse and human wound models, advancement in the scientific knowledge has the potential to promote the health and wellbeing of the patients.Through engaging with a wide audience through both academic, industrial collaborations, clinical patients and public engagement (summarised in the communications plan) will greatly enhance the impact of the research.