Could disguising allergens in the body treat asthma?
A group of US scientists are developing a novel technology that may revolutionise the treatment of asthma and allergies.
By “hiding” allergens inside miniscule nanoparticles injected directly into the bloodstream, they have been able to trick the immune system into ignoring substances that would normally cause an allergic reaction.
Asthma and other allergic diseases occur when the immune system misidentifies harmless substances like pollen (known as allergens or antigens) as a threat to the body, triggering a vigorous inflammatory response that causes symptoms such as itchiness, sneezing, coughing, shortness of breath and skin rashes.
Allergy shots (or immunotherapy) are a widely used to treat this condition. Over a lengthy period of time, the patient is exposed to gradually increasing doses of the antigen that sets off their allergic reaction. This desensitises them to the substance and reduces the severity of the symptoms.
Unfortunately, the procedure has some major downsides: it involves a considerable risk of unintended negative reactions and takes a long time to take effect. The new study promises significant improvements on both counts.
Nanoparticles are tiny bits of material less than 100 nanometres – that’s 0.0001 millimetres – in size. They have been employed to treat allergies and asthma in a laboratory environment with moderate success during the past few years.
The nanoparticles are used as carriers transporting antigens into the patient’s bloodstream. The breakthrough in the new study came when researchers enclosed the antigens inside the nanoparticles instead of simply coating them onto their outer surface.
Clinical trials soon
In a process that has been likened to the Trojan Horse of Greek mythology, the antigen is encapsulated inside tiny particles of a biodegradable material called poly(lactide-co-glycolide), or PLG. The immune system doesn’t consider these nanoparticles as harmful, allowing for the speedy, efficient and safe delivery of antigens which results in tolerance to the substance without causing detrimental side effects.
So far, the technique has been successfully implemented in mice, but the scientists are confident that it can soon be tested in clinical trials involving human patients.
Professor Stephen Miller, one of the co-authors of the study, describes the new method as a “universal treatment” that will be effective for a variety of allergic conditions. "Depending on what allergy you want to eliminate, you can load up the nanoparticle with ragweed pollen or a peanut protein."
As well as shutting down immune system attacks on specific antigens, the nanoparticle procedure also tends to increase the number of so-called regulatory T cells – specialised immune cells that aid the body in identifying harmless substances as they enter the airways and that have a calming effect on the immune system.
Drug delivery system
For allergy and asthma sufferers, the results are very promising. According to Miller, "the findings represent a novel, safe and effective long-term way to treat and potentially 'cure' patients with life-threatening respiratory and food allergies."
Applications involving nanoparticles are being explored in several other medical fields, including genetic and tissue engineering, the early detection of infectious diseases, gene therapy and the treatment of bacterial infections.
One area in which they are proving to be especially promising is as drug delivery systems. Attached to nanoparticles, medicines may be transported to specific sites, including disease locations, in the body and may be released en route as well as at the final destination.
The particles may, for instance, be designed to deliver chemotherapy drugs directly to cancer cells. In another example, nanoparticles that are sensitive to pressure may release drugs which dissolve blood clots when they pass through parts of an artery that are partially blocked by such a clot.