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Knee loading reduces MMP13 activity in the mouse cartilage.

Hamamura K, Zhang P, Zhao L, Shim JW, Chen A, Dodge TR, Wan Q, Shih H, Na S, Lin CC, Sun HB, Yokota H - BMC Musculoskelet Disord (2013)

Bottom Line: Load-driven reduction in MMP13 was associated with a decrease in the phosphorylation level of p38 MAPK (p-p38) and NFκB (p-NFκB).Silencing Rac1 GTPase significantly reduced MMP13 expression and p-p38 but not p-NFκB.Knee loading reduces MMP13 activity at least in part through Rac1-mediated p38 MAPK signaling.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, SL220C, 723 West Michigan Street, Indianapolis, IN 46202, USA. hyokota@iupui.edu.

ABSTRACT

Background: Moderate loads with knee loading enhance bone formation, but its effects on the maintenance of the knee are not well understood. In this study, we examined the effects of knee loading on the activity of matrix metalloproteinase13 (MMP13) and evaluated the role of p38 MAPK and Rac1 GTPase in the regulation of MMP13.

Methods: Knee loading (0.5-3 N for 5 min) was applied to the right knee of surgically-induced osteoarthritis (OA) mice as well as normal (non-OA) mice, and MMP13 activity in the femoral cartilage was examined. The sham-loaded knee was used as a non-loading control. We also employed primary non-OA and OA human chondrocytes as well as C28/I2 chondrocyte cells, and examined MMP13 activity and molecular signaling in response to shear at 2-20 dyn/cm².

Results: Daily knee loading at 1 N for 2 weeks suppressed cartilage destruction in the knee of OA mice. Induction of OA elevated MMP13 activity and knee loading at 1 N suppressed this elevation. MMP13 activity was also increased in primary OA chondrocytes, and this increase was attenuated by applying shear at 10 dyn/cm². Load-driven reduction in MMP13 was associated with a decrease in the phosphorylation level of p38 MAPK (p-p38) and NFκB (p-NFκB). Molecular imaging using a fluorescence resonance energy transfer (FRET) technique showed that Rac1 activity was reduced by shear at 10 dyn/cm² and elevated by it at 20 dyn/cm². Silencing Rac1 GTPase significantly reduced MMP13 expression and p-p38 but not p-NFκB. Transfection of a constitutively active Rac1 GTPase mutant increased MMP13 activity, while a dominant negative mutant decreased it.

Conclusions: Knee loading reduces MMP13 activity at least in part through Rac1-mediated p38 MAPK signaling. This study suggests the possibility of knee loading as a therapy not only for strengthening bone but also preventing tissue degradation of the femoral cartilage.

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BMD and BMC of the knee, distal femur, and proximal tibia in the three groups of mice (control, OA, and OA with knee loading). (A) BMD of the entire knee. (B) BMD of the distal femur. (C) BMD of the proximal tibia. (D) BMC of the entire knee. (E) BMC of the distal femur. (F) BMC of the proximal tibia. n = 6 per group (A-F).
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Figure 3: BMD and BMC of the knee, distal femur, and proximal tibia in the three groups of mice (control, OA, and OA with knee loading). (A) BMD of the entire knee. (B) BMD of the distal femur. (C) BMD of the proximal tibia. (D) BMC of the entire knee. (E) BMC of the distal femur. (F) BMC of the proximal tibia. n = 6 per group (A-F).

Mentions: Three weeks after induction of OA, the Safranin-O stained histological section of the right knee showed destruction of articular cartilage in the distal femur and proximal tibia (Figure 2A-B). When knee loading at 1 N was applied for 2 weeks 8 days after induction of OA, however, loss of surface staining was no longer observed (Figure 2B). In response to induction of OA, the histological score for the samples with knee loading was lowered compared to those without knee loading (age-matched control 4.29 ± 0.18; OA 5.3 ± 0.15; and OA + loaded 4.56 ± 0.18; N = 7). Furthermore, compared to the age-matched control, the OA control showed significant reduction in BMD and BMC in the entire knee, as well as in the distal femur and proximal tibia (Figure 3). Consistent with the histological observation of cartilage surfaces in the distal femur and proximal tibia, 2-week application of daily knee loading completely suppressed OA-induced reduction in BMD and BMC (Figure 3).


Knee loading reduces MMP13 activity in the mouse cartilage.

Hamamura K, Zhang P, Zhao L, Shim JW, Chen A, Dodge TR, Wan Q, Shih H, Na S, Lin CC, Sun HB, Yokota H - BMC Musculoskelet Disord (2013)

BMD and BMC of the knee, distal femur, and proximal tibia in the three groups of mice (control, OA, and OA with knee loading). (A) BMD of the entire knee. (B) BMD of the distal femur. (C) BMD of the proximal tibia. (D) BMC of the entire knee. (E) BMC of the distal femur. (F) BMC of the proximal tibia. n = 6 per group (A-F).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3924329&req=5

Figure 3: BMD and BMC of the knee, distal femur, and proximal tibia in the three groups of mice (control, OA, and OA with knee loading). (A) BMD of the entire knee. (B) BMD of the distal femur. (C) BMD of the proximal tibia. (D) BMC of the entire knee. (E) BMC of the distal femur. (F) BMC of the proximal tibia. n = 6 per group (A-F).
Mentions: Three weeks after induction of OA, the Safranin-O stained histological section of the right knee showed destruction of articular cartilage in the distal femur and proximal tibia (Figure 2A-B). When knee loading at 1 N was applied for 2 weeks 8 days after induction of OA, however, loss of surface staining was no longer observed (Figure 2B). In response to induction of OA, the histological score for the samples with knee loading was lowered compared to those without knee loading (age-matched control 4.29 ± 0.18; OA 5.3 ± 0.15; and OA + loaded 4.56 ± 0.18; N = 7). Furthermore, compared to the age-matched control, the OA control showed significant reduction in BMD and BMC in the entire knee, as well as in the distal femur and proximal tibia (Figure 3). Consistent with the histological observation of cartilage surfaces in the distal femur and proximal tibia, 2-week application of daily knee loading completely suppressed OA-induced reduction in BMD and BMC (Figure 3).

Bottom Line: Load-driven reduction in MMP13 was associated with a decrease in the phosphorylation level of p38 MAPK (p-p38) and NFκB (p-NFκB).Silencing Rac1 GTPase significantly reduced MMP13 expression and p-p38 but not p-NFκB.Knee loading reduces MMP13 activity at least in part through Rac1-mediated p38 MAPK signaling.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, SL220C, 723 West Michigan Street, Indianapolis, IN 46202, USA. hyokota@iupui.edu.

ABSTRACT

Background: Moderate loads with knee loading enhance bone formation, but its effects on the maintenance of the knee are not well understood. In this study, we examined the effects of knee loading on the activity of matrix metalloproteinase13 (MMP13) and evaluated the role of p38 MAPK and Rac1 GTPase in the regulation of MMP13.

Methods: Knee loading (0.5-3 N for 5 min) was applied to the right knee of surgically-induced osteoarthritis (OA) mice as well as normal (non-OA) mice, and MMP13 activity in the femoral cartilage was examined. The sham-loaded knee was used as a non-loading control. We also employed primary non-OA and OA human chondrocytes as well as C28/I2 chondrocyte cells, and examined MMP13 activity and molecular signaling in response to shear at 2-20 dyn/cm².

Results: Daily knee loading at 1 N for 2 weeks suppressed cartilage destruction in the knee of OA mice. Induction of OA elevated MMP13 activity and knee loading at 1 N suppressed this elevation. MMP13 activity was also increased in primary OA chondrocytes, and this increase was attenuated by applying shear at 10 dyn/cm². Load-driven reduction in MMP13 was associated with a decrease in the phosphorylation level of p38 MAPK (p-p38) and NFκB (p-NFκB). Molecular imaging using a fluorescence resonance energy transfer (FRET) technique showed that Rac1 activity was reduced by shear at 10 dyn/cm² and elevated by it at 20 dyn/cm². Silencing Rac1 GTPase significantly reduced MMP13 expression and p-p38 but not p-NFκB. Transfection of a constitutively active Rac1 GTPase mutant increased MMP13 activity, while a dominant negative mutant decreased it.

Conclusions: Knee loading reduces MMP13 activity at least in part through Rac1-mediated p38 MAPK signaling. This study suggests the possibility of knee loading as a therapy not only for strengthening bone but also preventing tissue degradation of the femoral cartilage.

Show MeSH
Related in: MedlinePlus