The Regulation of Aggrecanase ADAMTS-4 Expression in Human Achilles Tendon and tendon-Derived Cells

Several members of the ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin motifs) family have been identified as aggrecanases, whose substrates include versican, the principal large proteoglycan in the tendon extracellular matrix. We have characterized the expression of ADAMTS-4 in human Achilles tendon and tendon-derived cells. ADAMTS-4 mRNA levels were higher in ruptured tendon compared with normal tendon or chronic painful tendinopathy. In tissue extracts probed by Western blotting, mature ADAMTS-4 (68 kDa) was detected only in ruptured tendons, while processed ADAMTS-4 (53 kDa) was detected also in chronic painful tendinopathy and in normal tendon. In cultured Achilles tendon cells, transforming growth factor-ß (TGF-ß) stimulated ADAMTS-4 mRNA expression (typically 20-fold after 24 h), while interleukin-1 induced a smaller, shorter-term stimulation which synergised markedly with that induced by TGF-ß. Increased levels of immunoreactive proteins consistent with mature and processed forms of ADAMTS-4 were detected in TGF-ß-stimulated cells. ADAMTS-4 mRNA was expressed at higher levels by tendon cells in collagen gels than in monolayer cultures. In contrast, the expression of ADAMTS-1 and -5 mRNA was lower in collagen gels compared with monolayers, and these mRNA showed smaller or opposite responses to growth factors and cytokines compared with that of ADAMTS-4 mRNA. We conclude that both ADAMTS-4 mRNA and ADAMTS-4 protein processing may be differentially regulated in normal and damaged tendons and that both the matrix environment and growth factors such as TGF-ß are potentially important factors controlling ADAMTS aggrecanase activities in tendon pathology

Changes in matrix protein biochemistry and the expression of mRNA encoding matrix proteins and metalloproteinases in posterior tibialis tendinopathy

OBJECTIVES: Adult-acquired flat foot secondary to a dysfunctional posterior tibialis tendon (PTT) is often treated by surgical transfer of the flexor digitorum longus tendon (FDLT). In this study, the authors compared normal PTT, stage II dysfunctional PTT and replacement FDLT, aiming to define changes in collagen modification, glycosaminoglycan (GAG) and the expression of matrix and metalloproteinase mRNA. METHODS: Normal PTTs were obtained from patients with no history of tendon problems. Samples of dysfunctional PTT and replacement FDLT tissue were obtained from patients undergoing surgical reconstruction. Tissue samples were analysed for total collagen and GAG, pentosidine and collagen cross-links. Total RNA was assayed for mRNA encoding matrix proteins and metalloproteinases, using real-time reverse transcription PCR. Differences between clinical groups were assessed using non-parametric statistics. RESULTS: Dysfunctional PTT contained higher levels of GAG and lower levels of pentosidine than normal PTT or FDLT. In contrast, collagen in FDLT contained fewer ketoimine and more aldimine cross-links than either normal or dysfunctional PTT. mRNA encoding types I and III collagens, aggrecan, biglycan, matrix metalloproteinase (MMP)-2, -13 and -23, and a disintegrin and metalloproteinase (ADAM)-12L each showed increased levels in dysfunctional PTT compared with either normal PTT or (except MMP-13) FDLT. In contrast, MMP-3 and ADAM with thrombospondin domain (ADAMTS)-5 mRNA were lower in both dysfunctional PTT and FDLT than in normal PTT, while ADAMTS-1 mRNA was lower in dysfunctional PTT than in FDLT. CONCLUSIONS: Stage II dysfunctional PTT shows biochemical and molecular changes consistent with a chronic remodelling of the extracellular matrix, rather than rupture, while the replacement FDLT resembles normal PTT in many, but not all, parameters

Acute vitamin C improves cardiac function, not exercise capacity, in adults with type 2 diabetes

Abstract Background People with type 2 diabetes (T2D) have impaired exercise capacity, even in the absence of complications, which is predictive of their increased cardiovascular mortality. Cardiovascular dysfunction is one potential cause of this exercise defect. Acute infusion of vitamin C has been separately shown to improve diastolic and endothelial function in prior studies. We hypothesized that acute vitamin C infusion would improve exercise capacity and that these improvements would be associated with improved cardiovascular function. Methods Adults with T2D (n = 31, 7 female, 24 male, body mass index (BMI): 31.5 ± 0.8 kg/m2) and BMI-similar healthy adults (n = 21, 11 female, 10 male, BMI: 30.4 ± 0.7 kg/m2) completed two randomly ordered visits: IV infusion of vitamin C (7.5 g) and a volume-matched saline infusion. During each visit peak oxygen uptake (VO2peak), brachial artery flow mediated dilation (FMD), reactive hyperemia (RH; plethysmography), and cardiac echocardiography were measured. General linear mixed models were utilized to assess the differences in all study variables. Results Acute vitamin C infusion improved diastolic function, assessed by lateral and septal E:E’ (P < 0.01), but did not change RH (P = 0.92), or VO2peak (P = 0.33) in any participants. Conclusion Acute vitamin C infusion improved diastolic function but did not change FMD, forearm reactive hyperemia, or peak exercise capacity. Future studies should further clarify the role of endothelial function as well as other possible physiological causes of exercise impairment in order to provide potential therapeutic targets. Trial registration NCT00786019. Prospectively registered May 200

The Interaction between Genetic Ancestry and Breast Cancer Risk Factors among Hispanic Women: The Breast Cancer Health Disparities Study

Background: Hispanic women have lower breast cancer incidence rates than non-Hispanic white (NHW) women. To what extent genetic versus nongenetic factors account for this difference is unknown.Methods: Using logistic regression, we evaluated the interactive influences of established risk factors and ethnicity (self-identified and identified by ancestral informative markers) on breast cancer risk among 2,326 Hispanic and 1,854 NHW postmenopausal women from the United States and Mexico in the Breast Cancer Health Disparities Study.Results: The inverse association between the percentage of Native American (NA) ancestry and breast cancer risk was only slightly attenuated after adjusting for known risk factors [lowest versus highest quartile: odds ratio (OR) =1.39, 95% confidence interval (CI) = 1.00-1.92 among U.S. Hispanics; OR = 1.92 (95% CI, 1.29-2.86) among Mexican women]. The prevalence of several risk factors, as well as the associations with certain factors and breast cancer risk, differed according to genetic admixture. For example, higher body mass index (BMI) was associated with reduced risk among women with lower NA ancestry only [BMI &lt;25 versus &gt;30: OR = 0.65 (95% CI, 0.44-0.98) among U.S. Hispanics; OR = 0.53 (95% CI, 0.29-0.97) among Mexicans]. The average number of risk factors among cases was inversely related to the percentage of NA ancestry.Conclusions: The lower NA ancestry groups were more likely to have the established risk factors, with the exception of BMI. Although the majority of factors were associated with risk in the expected directions among all women, BMI had an inverse association among Hispanics with lower NA ancestry.Impact: These data suggest that the established risk factors are less relevant for breast cancer development among women with more NA ancestry. Cancer Epidemiol Biomarkers Prev; 26(5); 692-701. ©2016 AACR