Boards, Advisory Committees, Professional Organizations

  • Member, Japanese Orthopaedic Association (2012 - Present)
  • Member, Japan College of Rheumatology (2017 - Present)
  • Member, Japanese Society of Cartilage Metabolism (2017 - Present)
  • Member, Orthopaedic Research Society (2019 - Present)
  • Member, Japanese Society of Inflammation and Regeneration (2021 - Present)

Professional Education

  • Master of Medicine, Kyushu University (2021)
  • Doctor of Medicine, Kyushu University (2012)
  • Doctor of Philosophy, Kyushu University (2021)
  • Doctor of Medicine, Kyushu University (2012)
  • Ph.D., Graduated school of Kyushu University, School of Medicine (Fukuoka, Japan) (2021)
  • Board Certification, Rheumatologist of the Japanese Orthopaedic Association (2020)
  • Board Certification, Japanese Orthopaedic Association (2019)
  • M.D., Kyushu University, School of Medicine (Fukuoka, Japan) (2012)

Stanford Advisors

Current Research and Scholarly Interests

Rheumatoid Arthritis, Cartilage Metabolism

All Publications

  • G protein-coupled receptor kinase 5 deletion suppresses synovial inflammation in a murine model of collagen antibody-induced arthritis SCIENTIFIC REPORTS Toya, M., Akasaki, Y., Sueishi, T., Kurakazu, I., Kuwahara, M., Uchida, T., Tsutsui, T., Tsushima, H., Yamada, H., Lotz, M. K., Nakashima, Y. 2021; 11 (1): 10481


    G protein-coupled receptor kinase 5 (GRK5) regulates inflammatory responses via the nuclear factor-kappa B (NF-κB) pathway. This study investigated the functional involvement of GRK5 in the pathogenesis of inflammatory arthritis. Immunohistochemically, rheumatoid arthritis (RA) synovium had a significantly higher proportion of GRK5-positive cells in the synovial lining layer than healthy control synovium. Gene expression and NF-κB activation in lipopolysaccharide-stimulated human SW982 synovial cells were significantly suppressed by silencing of the GRK5 gene. Similarly, GRK5 kinase activity inhibition in human primary RA synovial cells attenuated gene expressions of inflammatory factors. In a murine model of collagen antibody-induced arthritis, arthritis scores and serum IL6 production of GRK5 knockout (GRK5-/-) mice were significantly lower than those of wild-type mice. Histologically, the degree of synovitis and cartilage degeneration in GRK5-/- mice was significantly lower than in wild-type mice. In in vitro analyses using activated murine macrophages and fibroblast-like synoviocytes, gene expression of inflammatory factors and p65 nuclear translocation were significantly lower in GRK5-/- mice compared to wild-type mice. In conclusion, our results suggested that GRK5 is deeply involved in the pathogenesis of inflammatory arthritis, therefore, GRK5 inhibition could be a potential therapeutic target for types of inflammatory arthritis such as RA.

    View details for DOI 10.1038/s41598-021-90020-0

    View details for Web of Science ID 000658858500013

    View details for PubMedID 34006987

    View details for PubMedCentralID PMC8131379

  • TGFβ1 signaling protects chondrocytes against oxidative stress via FOXO1-autophagy axis. Osteoarthritis and cartilage Kurakazu, I., Akasaki, Y., Tsushima, H., Sueishi, T., Toya, M., Kuwahara, M., Uchida, T., Lotz, M. K., Nakashima, Y. 2021; 29 (11): 1600-1613


    The forkhead box O1 (FOXO1) transcription factor is a key regulator of autophagy. In chondrocytes, reduced FOXO1 expression with aging causes osteoarthritis due to dysfunction of autophagy, but the mechanisms underlying regulation of FOXO1 expression and the reduction in expression with aging remain unclear. We investigated the mechanism by which transforming growth factor β1 (TGFβ1) signaling regulates the FOXO1-autophagy axis.Expression of FOXO1 was measured in chondrocytes after TGFβ1 treatment. Immunohistochemistry was performed to estimate the levels of activin receptor-like kinase 5 (ALK5) and FOXO1 in the knee joints of young, middle-aged and old mice. The effects of the ALK5 inhibitor and SMAD3 or SMAD2 knockdown on FOXO1 expression were evaluated. The role of TGFβ1 in autophagy after hydrogen peroxide (H2O2) treatment was analyzed. The protective effect of TGFβ1 against H2O2 treatment was assessed by cell viability assay and TUNEL assay.TGFβ1 promoted the expression of FOXO1 mRNA and protein. Both ALK5 and FOXO1 expression decreased with aging. ALK5 inhibition and SMAD3 knockdown suppressed induction of FOXO1 expression by TGFβ1, whereas SMAD2 knockdown increased it. TGFβ1 promoted the expression of microtubule-associated proteins 1A/1B light chain 3B (LC3)-I protein via the SMAD3-FOXO1 pathway. Furthermore, under H2O2 treatment, TGFβ1 promoted expression of LC3-II. TGFβ1 pretreatment suppressed cell death of chondrocytes following H2O2 treatment, but this protective effect was abolished by FOXO1 knockdown.TGFβ1 protects chondrocytes against oxidative stress via the FOXO1-autophagy axis, and a reduction in ALK5 expression might cause reduced FOXO1 expression with aging.

    View details for DOI 10.1016/j.joca.2021.07.015

    View details for PubMedID 34419603

  • Dedifferentiated low-grade central osteosarcoma with extensive cystic change initially treated as a simple bone cyst PATHOLOGY RESEARCH AND PRACTICE Toya, M., Yamada, Y., Yokoyama, R., Taguchi, K., Nabeshima, K., Isayama, T., Oda, Y. 2020; 216 (4): 152832


    Low-grade central osteosarcoma (LG-COS) is an uncommon variant of osteosarcoma (OS) that sometimes progresses to high-grade OS post-recurrence. We herein present a case of dedifferentiated LG-COS with extensive cystic change arising in the right iliac bone of a 26-year-old man. The LG-COS was initially diagnosed and managed as a simple bone cyst. The lesion recurred thrice, and high-grade OS was diagnosed during the third recurrence. The first lesion appeared as a typical benign cystic mass on radiography. However, a huge malignant osteoblastic mass subsequently developed in the right pelvis at the third recurrence. Extended hemipelvectomy with ipsilateral hemisacral resection was performed. Histologic analysis showed tumor necrosis and irregular neoplastic tumor osteoid, while immunohistochemistry revealed that the tumor was diffusely positive for MDM2 and CDK4. The histologic diagnosis was high-grade OS dedifferentiated from a preceding cystic lesion. Our final diagnosis of the primary lesion was LG-COS with extensive cystic change.

    View details for DOI 10.1016/j.prp.2020.152832

    View details for Web of Science ID 000523598700020

    View details for PubMedID 32057514

  • GRK5 Inhibition Attenuates Cartilage Degradation via Decreased NF-kappa B Signaling ARTHRITIS & RHEUMATOLOGY Sueishi, T., Akasaki, Y., Goto, N., Kurakazu, I., Toya, M., Kuwahara, M., Uchida, T., Hayashida, M., Tsushima, H., Bekki, H., Lotz, M. K., Nakashima, Y. 2020; 72 (4): 620-631


    NF-κB-dependent signaling is an important modulator in osteoarthritis (OA), and G protein-coupled receptor kinase 5 (GRK5) regulates the NF-κB pathway. This study was undertaken to investigate the functional involvement of GRK5 in OA pathogenesis.GRK5 expression in normal and OA human knee joints was analyzed immunohistochemically. Gain- or loss-of-function experiments were performed using human and mouse chondrocytes. OA was induced in GRK5-knockout mice by destabilization of the medial meniscus, and histologic examination was performed. OA was also induced in wild-type mice, which were then treated with an intraarticular injection of amlexanox, a selective GRK5 inhibitor, every 5 days for 8 weeks.GRK5 protein expression was increased in human OA cartilage. In vitro, expression levels of OA-related factors and NF-κB transcriptional activation were down-regulated by suppression of the GRK5 gene in human OA chondrocytes (3.49-fold decrease in IL6 [P < 0.01], 2.43-fold decrease in MMP13 [P < 0.01], and 2.66-fold decrease in ADAMTS4 [P < 0.01]). Conversely, GRK5 overexpression significantly increased the expression of OA-related catabolic mediators and NF-κB transcriptional activation. On Western blot analysis, GRK5 deletion reduced IκBα phosphorylation (up to 4.4-fold decrease [P < 0.05]) and decreased p65 nuclear translocation (up to 6.4-fold decrease [P < 0.01]) in mouse chondrocytes. In vivo, both GRK5 deletion and intraarticular amlexanox protected mouse cartilage against OA.Our results suggest that GRK5 regulates cartilage degradation through a catabolic response mediated by NF-κB signaling, and is a potential target for OA treatment. Furthermore, amlexanox may be a major compound in relevant drugs.

    View details for DOI 10.1002/art.41152

    View details for Web of Science ID 000522140900015

    View details for PubMedID 31696655

  • FOXO1 transcription factor regulates chondrogenic differentiation through transforming growth factor beta 1 signaling JOURNAL OF BIOLOGICAL CHEMISTRY Kurakazu, I., Akasaki, Y., Hayashida, M., Tsushima, H., Goto, N., Sueishi, T., Toya, M., Kuwahara, M., Okazaki, K., Duffy, T., Lotz, M. K., Nakashima, Y. 2019; 294 (46): 17555-17569


    The forkhead box O (FOXO) proteins are transcription factors involved in the differentiation of many cell types. Type II collagen (Col2) Cre-Foxo1-knockout and Col2-Cre-Foxo1,3,4 triple-knockout mice exhibit growth plate malformation. Moreover, recent studies have reported that in some cells, the expressions and activities of FOXOs are promoted by transforming growth factor β1 (TGFβ1), a growth factor playing a key role in chondrogenic differentiation. Here, using a murine chondrogenic cell line (ATDC5), mouse embryos, and human mesenchymal stem cells, we report the mechanisms by which FOXOs affect chondrogenic differentiation. FOXO1 expression increased along with chondrogenic differentiation, and FOXO1 inhibition suppressed chondrogenic differentiation. TGFβ1/SMAD signaling promoted expression and activity of FOXO1. In ATDC5, FOXO1 knockdown suppressed expression of sex-determining region Y box 9 (Sox9), a master regulator of chondrogenic differentiation, resulting in decreased collagen type II α1 (Col2a1) and aggrecan (Acan) expression after TGFβ1 treatment. On the other hand, chemical FOXO1 inhibition suppressed Col2a1 and Acan expression without suppressing Sox9 To investigate the effects of FOXO1 on chondrogenic differentiation independently of SOX9, we examined FOXO1's effects on the cell cycle. FOXO1 inhibition suppressed expression of p21 and cell-cycle arrest in G0/G1 phase. Conversely, FOXO1 overexpression promoted expression of p21 and cell-cycle arrest. FOXO1 inhibition suppressed expression of nascent p21 RNA by TGFβ1, and FOXO1 bound the p21 promoter. p21 inhibition suppressed expression of Col2a1 and Acan during chondrogenic differentiation. These results suggest that FOXO1 is necessary for not only SOX9 expression, but also cell-cycle arrest during chondrogenic differentiation via TGFβ1 signaling.

    View details for DOI 10.1074/jbc.RA119.009409

    View details for Web of Science ID 000503173500031

    View details for PubMedID 31601652

    View details for PubMedCentralID PMC6873195