In an important step towards treating arthritis in humans, Swiss scientists have fully cured the condition in mice for the first time using a new therapeutic product.
The scientists are planning to test the efficacy of the drug in humans next year.
Rheumatoid arthritis is a condition that causes painful inflammation of several joints in the body. The joint capsule becomes swollen, and the disease can also destroy cartilage and bone as it progresses.
The condition affects 0.5 per cent to 1 per cent of the world's population. Until now, doctors have used various drugs to slow or stop the progression of the disease.
But now, researchers at the Swiss Federal Institute of Technology in Zurich (ETHZ) have developed a therapy that takes the treatment of rheumatoid arthritis in mice to a new level: after receiving the medication, researchers consider the animals to be fully cured.
The drug is a biotechnologically produced active substance consisting of two fused components. One component is the body's own immune messenger interleukin 4 (IL-4); previous studies have shown that this messenger protects mice with rheumatoid arthritis against cartilage and bone damage.
Scientists coupled an antibody to IL-4 that, based on the key-lock principle, binds to a form of a protein that is found only in inflamed tissue in certain diseases.
"As a result of combination with the antibody, IL-4 reaches the site of the disease when the fusion molecule is injected into the body," said Teresa Hemmerle, who completed her dissertation in the group of Dario Neri, a professor at the Institute of Pharmaceutical Sciences.
"It allows us to concentrate the active substance at the site of the disease. The concentration in the rest of the body is minimal, which reduces side-effects," said Neri, the lead author of the study together with Fabia Doll, also a PhD pharmacist at ETH.
The researchers tested the new fusion molecule, which they refer to as an 'armed antibody'. They used a mouse model in which the animals developed swollen, inflamed toes and paws within a few days.
Researchers studied the fusion molecule in combination with dexamethasone, a cortisone-like anti-inflammatory drug already used to treat rheumatoid arthritis in humans.
They started treating each mouse as soon as they began showing signs of the disease in the form of swollen extremities.
When used separately, the new fusion molecule and dexamethasone managed only to slow the progression of the disease in the affected animals.
In contrast, the typical signs of arthritis, such as swollen toes and paws, disappeared completely within a few days when both medications were administered at the same time.
Concentrations of a whole range of immune messengers in blood and inflamed tissue, which are changed in rheumatoid arthritis, returned to their normal levels.
