'Sugar coating' clue to how parasitic worms dupe immune system

New study sheds new light on how people are infected with schistosomiasis<em> - News Release</em>

Imperial College London news release

For immediate use
Thursday 6 September 2007

Sugars secreted by a parasitic worm could provide the key to how it infects the human body and how its eggs escape to spread the deadly disease schistosomiasis, according to new research.

The study, published in the September 2007 edition of Molecular and Cellular Proteomics journal, has given scientists a greater understanding of complex sugars secreted by the Schistosoma mansoni worms and how they lead to successful infection of a human host. In the long term, understanding exactly how the worm evades the host's immune system could lead to the development of a vaccine or new treatments for schistosomiasis.

Schistosomiasis is a debilitating disease, affecting up to 200 million people in Asia, Africa and South America. The parasite enters the human body through the skin when people come into contact with fresh water where it lives. It can cause severe liver damage, blood loss and sometimes lead to death.

The research team from Imperial College London and the University of York suggests that the sugars secreted by the worm are vital to the worm's ability to hoodwink the host's immune system. Analysing the secreted sugars using mass spectrometry, the scientists found these worms' secretions contain a plethora of complex sugars that cannot be found in the human host.

Dr Stuart Haslam   from Imperial College London's Division Molecular Biosciences, lead author of the study, explains: "Sugars secreted into the host's skin when the worm penetrates have a key role to play in whether or not the host's immune system recognises the worm as a threat. Much in the way that a matador uses his cloak to distract the bull and prevent personal injury, so the secretions distract the immune system and prevent the real target, the worm, being attacked."

The researchers think that one possibility of how this works is that the sugars secreted are highly immunogenic, meaning they prompt the host's immune system to home in on them and attack. But by the time the host's anti-infection white blood cells reach the site of the sugars, the worm itself has already moved on to another place in the body.

"It's certainly possible that these worms use the sugars they secrete to throw the host's immune system off the scent, allowing them to move unimpeded through the body, to the liver where they begin to lay eggs," said Dr Haslam.

"Conversely, the parasite's eggs laid in the gut wall deliberately attract the immune system through the release of these immunogenic sugars, apparently fooling the host's immune cells into aiding their escape from the body."

"However, even though our study provides us with more clues than ever before as to precisely how these worms infect a host, and we now believe these sugars are key, more scientific investigations are needed to unravel exactly how these worms infect so many people around the world each year," he added.

For more information please contact:

Danielle Reeves, Imperial College London Press Office,
Tel: +44 (0)20 7594 2198
Mob: +44 (0)7803 886248
Email: Danielle.reeves@imperial.ac.uk

Notes to Editors:

1. "Glycomic analysis of Schistosoma mansoni egg and cercarial secretions" Molecular and Cellular Proteomics, September 2007.

Jihye Jang-Lee (1), Rachel S. Curwen (2), Peter D. Ashton (2), Bérangère Tissot (1), William Mathieson (2), Maria Panico (1), Anne Dell (1), R. Alan Wilson (2) and Stuart M. Haslam (1).

(1) Division of Molecular Biosciences, Imperial College London SW7 2AZ, UK
(2) Department of Biology, University of York, York YO10 5YW, UK

This work was supported in part by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Wellcome Trust and by additional funds from the United Nations Development Programme/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases.

2. Rated as the world’s ninth best university in the 2006 Times Higher Education Supplement University Rankings, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 11,500 students and 6,000 staff of the highest international quality.

Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.

With 66 Fellows of the Royal Society among our current academic staff and distinguished past members of the College including 14 Nobel Laureates and two Fields Medallists, Imperial's contribution to society has been immense. Inventions and innovations include the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of our research for the benefit of all continues today with current focuses including interdisciplinary collaborations to tackle climate change and mathematical modelling to predict and control the spread of infectious diseases.

The College's 100 years of living science will be celebrated throughout 2007 with a range of events to mark the Centenary of the signing of Imperial's founding charter on 8 July 1907.

Website: www.imperial.ac.uk

3. The University of York's Department of Biology is one of the leading centres for biological teaching and research in the UK. The Department, with more than 400 scientific and support staff and 400 undergraduates currently has one of the highest research ratings in the UK.