The University of Southampton
Medicine
Email:
J.Ratnayaka@soton.ac.uk

Dr J Arjuna Ratnayaka BSc, MPhil, PhD

Lecturer in Vision Sciences

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Dr J Arjuna Ratnayaka is Lecturer in Vision Sciences within Medicine at the University of Southampton.

Dr Ratnayaka is a lecturer in Vision Sciences and brings together expertise in Retinal biology and Neurodegeneration. Dr Ratnayaka graduated from the University of Aberdeen. Following a Masters at Imperial College, London, he completed his PhD at the University of Liverpool where his work characterised the molecular/biochemical fate of a gene associated with Age-related Macular Degeneration (AMD). His work also investigated the intracellular trafficking of osteonectin/SPARC, a critical modulator in Proliferative Vitreoretinopathy (PVR). He extended his interests in degenerative biology in two successive research groups at King’s College, London and at the University of Sussex, where his postdoctoral work investigated axonal and synaptic mechanisms in the central nervous system. His work helped unravel the molecular pathways of neurotransmission by describing how shared vesicle pools may be utilized by neighbouring synapses, how extra-synaptic signalling occurs, and the manner in which distinct vesicle pools are modulated in synaptic plasticity.

His group at Southampton investigates the molecular mechanisms underlying degenerative pathologies, with a particular focus on diseases of the retina. Currently, there are a number of exciting projects employing a range of cutting-edge techniques including ex-vivo and in-vivo disease modelling, live/ultrastructural imaging, molecular biology, histological and biochemical approaches.

Dr Ratnayaka collaborates with scientists and clinicians from within and outside the University of Southampton, and networks with industrial partners as well as with patients/support groups. His portfolio includes teaching and mentoring activities across BSc, BMedSc, MSc, as well as PhD programmes in several Faculties. He is also involved in raising awareness of the implications of major degenerative diseases such as AMD and Alzheimer’s disease through public lectures, awareness days and education in schools.

Qualifications

BSc (Hons) Biochemistry/Immunology, University of Aberdeen with a year industrial placement (Zeneca Pharmaceuticals), (1998)
MPhil, DIC Medicine (Microbiology), Imperial College, London (2001)
PhD Metabollic and Cellular Medicine, University of Liverpool (2007)

Appointments held

Research Scientist, University of Manchester (2000-2001)

Research Assistant/Associate, University of Liverpool (2003-2006)

Postdoctoral Researcher, King’s College, London (2006-2009)

Research Fellow and Assistant Tutor, University of Sussex (2009-2013)

Lecturer in Vision Sciences, Faculty of Medicine, University of Southampton (2013-present)

Research

Responsibilities

Publications

Teaching

Contact

My group studies fundamental mechanisms of degenerative disorders at the level of molecules and cells. These include major diseases of the retina and brain such as Age-related Macular degeneration (AMD) which leads to irreversible blindness, and Alzheimer’s disease (AD) which is associated with dementia. Diseases of the retina and brain have complex aetiologies, but share striking similarities including impaired trafficking/transport processes, damaged intracellular organelles, misfolded proteins as well as common trigger mechanisms such as inflammation that can potentially initiate and/or sustain pathology. Collectively, these disorders contribute to a substantial proportion of major chronic diseases in the elderly, significantly impacting their quality of life in old age. Treatments for such conditions are typically non-existent or largely ineffective due to the complex nature of these diseases as well as a critical gap in our understanding of fundamental pathobiology. For example, VEGF (Vascular Endothelial Growth Factor) inhibitors form the current mainstay against neovascular AMD, but is only successful in managing the disease in a sub-group of AMD patients. In contrast, there is no effective treatment against the more common geographic form of AMD. With a rapidly aging population, this has created an urgent, and as yet unmet, need to understand the disease process, and help design/develop effective treatments for the future.

There are a number of exciting projects which run in parallel and interlink under major research themes that employ a range of techniques. Some common methods used in our studies are: live-confocal imaging, ultrastructural techniques such as light-sheet, scanning block-face, TEM/SEM microscopy, ex-vivo and in-vivo disease modelling, molecular biology, histological as well as biochemical approaches.

Investigating degenerative changes in the ageing retina

There are a variety of rare and common diseases of the retina, one of the most widespread being Age-related Macular Degeneration (AMD) which affects approximately 50 million individuals globally. AMD affects individuals over the age of 50 with 25% of the population in their 8th decade suffering from loss of central vision. Although AMD is well characterised clinically, the underlying mechanisms remain incompletely understood. Central to disease onset and progression is the impairment of the Retinal Pigment Epithelium (RPE), a monolayer of cells beneath the neuroretina. In the posterior eye, the RPE carries out critical functions including maintaining the light-sensitive photoreceptors, forming the blood-retinal barrier, removal of reactive oxygen/nitrogen species and supporting retinal adhesion amongst others. Consequently, any damage to this important monolayer has major implication for normal retinal homeostasis and risk of potential disease. Using a combination of ex-vivo systems and in-vivo models in parallel, we investigate key molecular and cellular changes associated with RPE and neuroretinal impairment in the ageing eye. Insights from our work will help define retinal diseases in novel molecular terms, and help identify new targets for future treatments.

Investigating links between the degenerating retina and the brain

Degenerative disorders of the retina and brain share remarkable similarities at both molecular and cellular level, some of which includes impairment of intracellular organelles and formation of toxic intra and extracellular protein aggregates. The interrelationships between the retina and brain also manifest clinically. These links have become more evident with recent findings showing structural irregularities in the retina and abnormalities in vision reported in patients with AD as well as other types of neurodegenerative diseases. Using cell culture systems as well as animal models of AMD and AD, projects in this theme draws parallels between degenerative events in these intimately related tissues, and studies them from a common perspective for insights into underlying disease processes.

Design and development of biosynthetic scaffolds- potential treatments for patients with blinding diseases

This is a collaborative effort with Prof Andrew Lotery to develop novel synthetic scaffolds as a potential therapy for patients with retinal disorders including AMD and Retinitis Pigmentosa. Here, artificial scaffolds are developed via established techniques, as well as electrospinning, laser-technologies and 3D printing which promise to create highly versatile materials for a range of biomedical and industrial applications. The efficacy of new scaffolds is tested in long-term cultures and in in-vivo models with the aim of providing rapid clinical benefits to patients with blinding disorders.

Investigating links between diabetes and retinal degeneration

The role of an individual’s diet and body mass has been shown to play an important role in the risk of developing some types of degenerative diseases. For instance, the intake of a high-fat cholesterol-rich diet over a lifetime forms a major environmental risk factor for AMD. Using primarily animal models of diabetes and AMD, this project studies how/when certain diets contribute to the onset of pathobiology in the aging retina. This is a collaborative effort with Dr Cagampang that can potentially reveal new insights into obesity and diseases of the eye.

Research Opportunities: Inquiries are welcomed from scientists, clinicians and industrial partners to work on potential projects utilizing expertise developed in our laboratory. Interlinking research themes spanning diseases of the eye and brain helps view these diseases from a novel perspective and creates an exceptional environment, ideal for postdoctoral scientists, particularly those with Fellowships. Currently, there is a vacancy for a prestigious Macular Society-funded PhD studentship due to commence in autumn 2015. Potential candidates (UK/EU) are encouraged to apply via the University of Southampton application portal, or contact Dr Ratnayaka for informal discussions. Inquiries are also welcomed from self-funded non-UK/EU students interested in undertaking research leading to a PhD award. Undergraduate and postgraduate students from the University of Southampton interested in short-term projects within this programme are also encouraged to contact Dr Ratnayaka in the first instance.

RPE monolayers in biosynthetic models of the outer retinal complex
Figure 1
Studies of organelle ultrastructure in retinal pathologies
Figure 2
Biosynthetic scaffolds for transplantation therapy (collaboration with Prof Lotery)
Figure 3
In-vivo disease modelling of AMD and AD
Figure 4

Research group

Clinical and Experimental Sciences Academic Units

Affiliate research group

Clinical Neuroscience Research group

Undergraduate and postgraduate supervision

Principal supervisor for the following students

2015: Louis Taylor, BMedSc student
2014: Savannah Lynn, PhD student
2014: Tommy Freeman, MSc student
2014: Aaron Kendall, BMedSc student
2014: Gagandeep Gabha, BSc student

Co-supervisor for the following students

2014: Gareth Ward, PhD student

University of Southampton

Southampton Neuroscience Group (SoNG): Steering committee
Institute for Life Sciences (IfLS): Member
Southern Network, Alzheimer’s Research UK: Committee member

External: Teaching

Lifelab, ‘Meet the scientist’ teaching sessions (secondary level education)

National and International responsibilities

Invited speaker for charities and patient support groups
Member- The Association for Research in Vision and Ophthalmology (ARVO)
Peer-reviewer for several scientific journals and major grant awarding bodies

Articles

Book Chapter

BM5: Lectures (Common mechanisms in degenerative diseases)

BMedSc: project supervision

BIOL3034: In depth research projects

BIOL6013: In depth research projects

Dr J Arjuna Ratnayaka
Tel: +44 (0)23 8120 8183 Email: J.Ratnayaka@soton.ac.uk

Email:J.Ratnayaka@soton.ac.uk

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