http://www.medscape.com/viewarticle/569113_6
Molecular Pathology of Tendinopathy
Biochemical and molecular studies of chronic tendinopathy during the past 15 years have increased our understanding of the underlying pathology; the main findings are summarized in Figure 2. In pathologic human tendon, there is increased expression of the messenger RNA of collagen types I and III, and increased amounts of type III collagen protein are found in the tendon matrix.[33] The levels of fibronectin and tenascin C are also increased, consistent with a healing response.[33] There is an increased level of glycosaminoglycan in the matrix33 and increased expression of the chondroitin sulfate proteoglycans, aggrecan and biglycan, even in the midsubstance of the Achilles tendon (in which fibrocartilage is not normally found), consistent with an adaptive response to shear or compression.[34] Versican messenger RNA levels were unchanged in painful tendons, although there were changes in splicing of the gene that would affect the quantity of glycosaminoglycan attached to the mature protein.[35]
The researchers Dr G P Riley, Professor J S H Gaston, Dr B L Hazleman, Dr G C Jones and Dr A N Corps have a long history of investigating tendon disease, and have recently generated exciting new information. The team has shown that production of an enzyme known as MMP-23 is increased in painful Achilles tendons and they plan to study its role in the development of tendon problems. MMP-23 is one member of a family of enzymes which break down the proteins that make up our connective tissues. However very little is known about the role and function of this recently discovered enzyme.
