Eyelid protein is key to allergy
Scientists have found a protein in the eye which plays a critical role in the development of an allergic response.
The University College London team say blocking the action of the protein may lead to new treatments for allergic diseases. Allergies affect over one third of people in the West. Some 17m people in the UK have asthma, conjunctivitis, eczema or hay fever. Details are published in the Journal of Clinical Investigation. Working on mice, the researchers found the protein – known as MIP-1a – plays a crucial role in the earliest stages of a developing eye allergy. They believe the same protein, or similar molecules, also play a similar role in the development of many other allergies. And they believe it should be possible to develop drug treatments to block the protein and thus prevent allergies from taking hold. Two phases Allergic responses develop in two phases. The first phase involves an immediate hypersensitivity reaction within one hour of exposure to an allergen. In this phase mast cells – which are responsible for causing allergies – release histamine and other molecules such as chemokines. MIP-1a is one such chemokine. The second phase, which occurs 12 to 24 hours after exposure, involves the recruitment of inflammatory cells to the site of inflammation. The UCL team discovered that MIP-1a plays a key role in the early stages of an allergic response within the clear membrane that coats the inner surface of the eyelid and outer surface of the eye, known as the conjunctiva. MIP-1a was also necessary for the second phase of the disease, which is associated with chronic allergy. Lead researcher Professor Santa Jeremy Ono said current treatments for severe eye allergy were either ineffective, or have side effects, such as glaucoma and cataract formation. His team is testing existing drugs that block MIP-1a and similar molecules. “Since we have found that MIP-1a is important for very early stages of allergy, the treatment may be more effective than drugs that work at late stages of the disease process, such as anti-histamines. “This would however be a treatment and not a cure. However, we do have some evidence that the drug may be effective for longer periods of time than existing medications.” Cautious welcome Dr Mike Matthews, chairman of Allergy UK, said: “The current treatment for allergies with antihistamines and steroids have potential unwanted effects in other areas and are a blunt weapon at best. “Anything that determines the nature of the allergic reaction more precisely will enable drugs to be developed that may be both more effective and safer. “The discovery of MIP-1a is good news for allergy sufferers. “It is likely to be a number of years before any drug based on this discovery reaches the market, but it is an excellent start point.” (Source: Journal of Clinical Investigation, BBC Health, January 2005)