title: Role of TGF-beta1 in relation to exercise-induced type I collagen synthesis in human tendinous tissue.
abstract: Mechanical loading of tissue is known to influence local collagen synthesis, and microdialysis studies indicate that mechanical loading of human tendon during exercise elevates tendinous type I collagen production. Transforming growth factor-beta1 (TGF-beta1), a potent stimulator of type I collagen synthesis, is released from cultured tendon fibroblasts in response to mechanical loading. Thus TGF-beta1 could link mechanical loading and collagen synthesis in tendon tissue in vivo. Tissue levels of TGF-beta1 and type I collagen metabolism markers [procollagen I COOH-terminal propeptide (PICP) and COOH-terminal telopeptide of type I collagen (ICTP)] were measured by microdialysis in peritendinous tissue of the Achilles' tendon in six male volunteers before and after treadmill running (1 h, 12 km/h, 3% uphill). In addition, blood levels of TGF-beta1, PICP, and ICTP were obtained. PICP levels increased 68 h after exercise (P < 0.05). Dialysate levels of TGF-beta1 changed from 303 +/- 46 pg/ml (at rest) to 423 +/- 86 pg/ml 3 h postexercise. This change was nonsignificant, but the decay of tissue TGF-beta1 after catheter insertion was markedly delayed by exercise compared with the decay seen in resting subjects. Plasma concentrations of TGF-beta1 rose 30% in response to exercise (P < 0.05 vs. pre). Our observations indicate an increased local production of type I collagen in human peritendinous tissue in response to uphill running. Although not conclusive, changes in circulating and local TGF-beta1, in response to exercise, suggest a role for TGF-beta1 in mechanical regulation of local collagen type I synthesis in tendon-related connective tissue in vivo.
authors.affiliation: Department of Rheumatology H, Bispebjerg Hospital, DK-2400 Copenhagen, Denmark. kh08@bbh.hosp.dk
authors.forename: Katja
authors.initials: K
authors.lastname: Heinemeier
authors.forename: Henning
authors.initials: H
authors.lastname: Langberg
authors.forename: Jens L
authors.initials: JL
authors.lastname: Olesen
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
mesh_terms: D000125:Achilles Tendon / Q000378:metabolism / Q000502:physiology; D000328:Adult; D015415:Biomarkers; D024042:Collagen Type I / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D015444:Exercise / Q000502:physiology*; D005109:Extracellular Matrix / Q000378:metabolism; D006400:Hematocrit; D006801:Humans; D008297:Male; D017551:Microdialysis; D013710:Tendons / Q000378:metabolism* / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000097:blood / Q000502:physiology*
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D016212:Transforming Growth Factor beta