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Disrupting the Indian hedgehog signaling pathway in vivo attenuates surgically induced osteoarthritis progression in Col2a1-CreERT2; Ihhfl/fl mice.

ABSTRACT: Previous observations implicate Indian hedgehog (Ihh) signaling in osteoarthritis (OA) development because it regulates chondrocyte hypertrophy and matrix metallopeptidase 13 (MMP-13) expression. However, there is no direct genetic evidence for the role of Ihh in OA, because mice with cartilage or other tissue-specific deletion of the Ihh gene die shortly after birth. We evaluated the role of Ihh in vivo via a Cre-loxP-mediated approach to circumvent the early death caused by Ihh deficiency.To evaluate the role of Ihh in OA development, Ihh was specifically deleted in murine cartilage using an Ihh conditional deletion construct (Col2a1-CreER(T2); Ihh(fl/fl)). The extent of cartilage degradation and OA progression after Ihh deletion was assessed by histological analysis, immunohistochemistry, real-time PCR and in vivo fluorescence molecular tomography (FMT) 2 months after OA was induced by partial medial meniscectomy. The effect of Ihh signaling on cartilage was compared between Ihh-deleted mice and their control littermates.Only mild OA changes were observed in Ihh-deleted mice, while control mice displayed significantly more cartilage damage. Typical OA markers such as type X collagen and MMP-13 were decreased in Ihh-deleted mice. In vivo FMT demonstrated decreased cathepsins and MMP activity in knee joints of animals with deletion of Ihh.These findings support the protective role of Ihh deletion in surgically induced OA. Thus, our findings suggest the potential to develop new therapeutic strategies that can prevent and treat OA by inhibiting Ihh signaling in chondrocytes.

SUBMITTER: Zhou J

PROVIDER: S-EPMC3978435 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature

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Disrupting the Indian hedgehog signaling pathway in vivo attenuates surgically induced osteoarthritis progression in Col2a1-CreERT2; Ihhfl/fl mice.

Zhou Jingming J Chen Qian Q Lanske Beate B Fleming Braden C BC Terek Richard R Wei Xiaochun X Zhang Ge G Wang Shaowei S Li Kai K Wei Lei L

Arthritis research & therapy 20140115 1

<h4>Introduction</h4>Previous observations implicate Indian hedgehog (Ihh) signaling in osteoarthritis (OA) development because it regulates chondrocyte hypertrophy and matrix metallopeptidase 13 (MMP-13) expression. However, there is no direct genetic evidence for the role of Ihh in OA, because mice with cartilage or other tissue-specific deletion of the Ihh gene die shortly after birth. We evaluated the role of Ihh in vivo via a Cre-loxP-mediated approach to circumvent the early death caused b ...[more]

PMID: 24428864

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Project description:The present study assessed the effects of microRNA-1 (miR-1) on the development of osteoarthritis using human tissues and a Col2a1-Cre-ERT2/GFPfl/fl-RFP-miR-1 mouse model of osteoarthritis. Human cartilage tissues (n=20) were collected for reverse transcription-quantitative polymerase chain reaction (RT-qPCR), histological analysis and immunohistochemistry experiments. A transgenic mouse model of osteoarthritis was established by subjecting Col2a1-Cre-ERT2/GFPfl/fl-RFP-miR-1 transgenic mice to anterior cruciate ligament transection (ACLT). Mice were subjected to radiography and in vivo fluorescence molecular tomography (FMT), while mouse tissues were collected for histological analysis, RT-qPCR and Safranin O staining. It was found that the miR-1 level was downregulated, whereas the levels of Indian hedgehog (Ihh), as well as those of its downstream genes were upregulated in human osteoarthritic cartilage. In the transgenic mice, treatment with tamoxifen induced miR-1, as well as collagen, type II (Col2a1) and Aggrecan (Acan) expression; however, it decreased Ihh, glioma-associated oncogene homolog (Gli)1, Gli2, Gli3, smoothened homolog (Smo), matrix metalloproteinase (MMP)-13 and collagen type X (Col10) expression. Safranin O staining revealed cartilage surface damage in the non-tamoxifen + ACLT group, compared with that in the tamoxifen + ACLT group. Histologically, an intact cartilage surface and less fibrosis were observed in the tamoxifen + ACLT group. Immunohistochemistry revealed that the protein expression of Ihh, Col10, and MMP-13 was significantly higher in the joint tissues of the non-tamoxifen + ACLT group than in those of the tamoxifen + ACLT group. However, Col2a1 expression was lower in the joint tissues of the non-tamoxifen + ACLT group than in those of the tamoxifen + ACLT group. The results of RT-qPCR and FMT further confirmed these findings. On the whole, the findings of the present study demonstrate that miR-1 expression protects against osteoarthritis-induced cartilage damage and gene expression by inhibiting Ihh signaling.

Project description:BackgroundTo determine if ipriflavone, a novel and safe inhibitor of Indian hedgehog (Ihh) signaling, can attenuate cartilage degeneration by blocking the Ihh pathway.MethodsHuman chondrocytes were used to evaluate Ihh signaling, cell proliferation, apoptosis, gene, and protein expression of chondrocytes by cell proliferation and apoptosis assays, real-time qPCR, and Western blotting at 48 h after ipriflavone treatment. Human cartilage explants were further used to validate the cell culture results. The effects of ipriflavone on cartilage degeneration in vivo were assessed using the rat ACLT OA model. Two-month-old male SD rats were randomized into 3 groups (n = 75): (1) sham, (2) ACLT alone, and (3) ACLT+ ipriflavone. Ipriflavone was administered intragastrically at 24 h after ACLT for 6 weeks. The extent of OA progression was evaluated by the OARSI score and immunohistochemistry at 12 weeks after surgery. The Ihh signaling pathway and OA-related genes were quantified by real-time PCR.ResultsCell proliferation in the cells treated with ipriflavone was increased to 36.40% ± 1.32% (5 μM) and 28.54% ± 0.74% (10 μM) from 11.99% ± 0.35% (DMSO) (P < 0.001), and apoptosis was decreased to 12.64% ± 3.7% (5 μM) and 15.18% ± 3.13% (10 μM) from 25.76% ± 5.1% (DMSO) (P < 0.05). Ipriflavone blocked Runx-2 mainly through the Smo-Gli2 pathway. A similar result was found in the cartilage explant culture. Ihh signaling in vivo was inhibited in animals treated with ipriflavone. Safranin-O staining revealed a less cartilage damage with lower OARSI scores (P < 0.05) in the ipriflavone-treated animals compared with untreated animals. The gene expression of Smo and Gli2 was inhibited significantly by ipriflavone (P < 0.05). The OA-related gene and protein type X, MMP-13, and type II collagen-C fragment were reduced, while type II collagen and Agg were increased in the ipriflavone-treated animals (P < 0.05).ConclusionsCatabolic genes were disrupted by blocking the Ihh pathway. This finding suggests that disruption of Ihh signaling with ipriflavone provides chondral protection in rat posttraumatic OA.

Dataset Information

Disrupting the Indian hedgehog signaling pathway in vivo attenuates surgically induced osteoarthritis progression in Col2a1-CreERT2; Ihhfl/fl mice.

Publications

Disrupting the Indian hedgehog signaling pathway in vivo attenuates surgically induced osteoarthritis progression in Col2a1-CreERT2; Ihhfl/fl mice.

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