Objective. To profile the messenger RNA (mRNA) expression for the 23 known genes of matrix metalloproteinases (MMPs), 19 genes of ADAMTS, 4 genes of tissue inhibitors of metalloproteinases (TIMPs), and ADAM genes 8, 10, 12, and 17 in normal, painful, and ruptured Achilles tendons.Methods. Tendon samples were obtained from cadavers or from patients undergoing surgical procedures to treat chronic painful tendinopathy or ruptured tendon. Total RNA was extracted and mRNA expression was analyzed by quantitative real-time reverse transcription-polymerase chain reaction, normalized to 18S ribosomal RNA.Results. In comparing expression of all genes, the normal, painful, and ruptured Achilles tendon groups each had a distinct mRNA expression signature. Three mRNA were not detected and 14 showed no significant difference in expression levels between the groups. Statistically significant (P < 0.05) differences in mRNA expression, when adjusted for age, included lower levels of MMPs 3 and 10 and TIMP-3 and higher levels of ADAM-12 and MMP-23 in painful compared with normal tendons, and lower levels of MMPs 3 and 7 and TIMPs 2, 3, and 4 and higher levels of ADAMs 8 and 12, MMPs 1, 9, 19, and 25, and TIMP-1 in ruptured compared with normal tendons.Conclusion. The distinct mRNA profile of each tendon group suggests differences in extracellular proteolytic activity, which would affect the production and remodeling of the tendon extracellular matrix. Some proteolytic activities are implicated in the maintenance of normal tendon, while chronically painful tendons and ruptured tendons are shown to be distinct groups. These data will provide a foundation for further study of the role and activity of many of these enzymes that underlie the pathologic processes in the tendon.

Repetitive strain or ‘overuse’ is thought to be a major factor contributing to the development of tendinopathy. The aims of our study were to develop a novel cyclic loading system, and use it to investigate the effect of defined loading conditions on the mechanical properties and gene expression of isolated tendon fascicles. Tendon fascicles were dissected from bovine-foot extensors and subjected to cyclic tensile strain (1 Hz) at 30% or 60% of the strain at failure, for 0 h (control), 15 min, 30 min, 1 h, or 5 h. Post loading, a quasi-static test to failure assessed damage. Gene expression at a selected loading regime (1 h at 30% failure strain) was analyzed 6 h post loading by quantitative real-time polymerase chain reaction. Compared with unloaded controls, loading at 30% failure strain took 5 h to lead to a significant decrease in failure stress, whereas loading to 60% led to a significant reduction after 15 min. Loading for 1 h at 30% failure strain did not create significant structural damage, but increased Collagen-1-alpha-chain-1 and interleukin-6 (IL6) expression, suggesting a role of IL6 in tendon adaptation to exercise. Correlating failure properties with fatigue damage provides a method by which changes in gene expression can be associated with different degrees of fatigue damage.

Three mammalian ADAMTS enzymes, ADAMTS-1, -4 and -5, are known to cleave aggrecan at certain glutamyl bonds and are considered to be largely responsible for cartilage aggrecan catabolism observed during the development of arthritis. We have previously reported that certain catechins, polyphenolic compounds found in highest concentration in green tea (Camellia sinensis), are capable of inhibiting cartilage aggrecan breakdown in an in vitro model of cartilage degradation. We have now cloned and expressed recombinant human ADAMTS-1, -4 and -5 and report here that the catechin gallate esters found in green tea potently inhibit the aggrecan-degrading activity of these enzymes, with submicromolar IC 50 values. Moreover, the concentration needed for total inhibition of these members of the ADAMTS group is approximately two orders of magnitude lower than that which is needed to partially inhibit collagenase or ADAM-10 activity. Catechin gallate esters therefore provide selective inhibition of certain members of the ADAMTS group of enzymes and could constitute an important nutritional aid in the prevention of arthritis as well as being part of an effective therapy in the treatment of joint disease and other pathologies involving the action of these enzymes.Keywords: ADAMTS; enzyme inhibition; catechin; gallate; aggrecanase.Green tea, made from the leaves of Camellia sinensis, contains catechins, a group of polyphenolic compounds with antioxidant properties that have been at the centre of investigations into the potential medical benefits of consuming green tea. The most abundant catechin in green tea is (-)-epigallocatechin gallate (EGCG) with others such as (-)-epicatechin (EC), (-)-epigallocatechin (EGC) and (-)-epicatechin gallate (ECG) also present. Anti-inflammatory and anti-mitotic properties have been attributed to these compounds [1-3] and they have also been reported to inhibit certain matrixins such as the gelatinases [4][5][6]. The beneficial effects on a range of clinical conditions including cancer growth and metastasis [7][8][9][10][11], cardiovascular and liver diseases [12] may therefore be due to one or a combination of these properties.Aggrecan, a large aggregating proteoglycan, is together with type II collagen the major constituent of articular cartilage. Degradation of cartilage aggrecan has mainly been attributed to the action of glutamyl endopeptidases, termed ÔaggrecanasesÕ. Aggrecan degradation products resulting from aggrecanase action have been found in in vitro cultures of cartilage treated with proinflammatory cytokines as well as in synovial fluid of arthritis patients [13][14][15][16]. To date three mammalian ÔaggrecanasesÕ have been identified: a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1, -4 and -5 [17][18][19]. The ADAMTS enzymes belong to a subgroup of metallopeptidases in Family M12 of Clan MA in the Merops database [20] and are related to the ADAMs and matrixins [21]. So far, at least 18 mammalian ADAMTS enzymes have been identified, most of which remain t...

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