'New protein jab could fight arthritis pain'

Researchers claim to have developed a potential new gene therapy technique for arthritis, paving way for a jab that could protect joints from a lifetime of wear and tear.
Scientists led by Dr Brendan Lee, professor of molecular and human genetics at Baylor College of Medicine unravel the effects of a naturally occurring protein called lubricin or Proteoglycans 4 that appears to protect against aging as well as helping with post-injury related changes.
"This protein also affects the metabolism of the cartilage and does it in a way that prevents its breakdown," said Lee.
Merry ZC Ruan, in Lee's laboratory, developed a special imaging technique called phase contrast ultra-high resolution micro-computed tomography (micro-CT) that allowed researchers to not only "see" the tiny cartilage in the knee joint but to also quantify that amount in the mouse joint.

To identify new targets for treating osteoarthritis (OA), they focused on a genetic disease in which the disorder starts early in children. These individuals are deficient in lubricin for, the protein in their joints made by special cells in the joint cartilage as well as by the cells that line part of the joint.
Researchers then studied mice that produced higher levels of the protein in cartilage, and found first that the animals acted and grew normally, suggesting that increased amounts of this protein was not harmful.

However, mice with an injury to their knees did not develop traumatic or injury-induced osteoarthritis.

Using the specially developed microscopy technique in these mice with high levels of lubricin, Lee and his colleagues determined that the mice did not have cartilage changes usually associated with osteoarthritis.
As the mice that made extra lubricin aged, their cartilage resembled that of young mice, Lee said in a statement. There was no osteoarthritis suggesting that this protein may protect against the two common forms of OA- injury-related and age-related.
Eventually, Lee and Ruan tried a gene therapy on normal mice, using a specially developed virus to inject the gene into the joints of the mice.
"The lubricin protein was expressed for the life of the mouse after a single injection into the joint," Lee said.

Moreover, the injection similarly protected the mouse against the development of injury-related OA.