Function of ERp57 in the development and progression of osteoarthritis in the knee joint

• Applicant: Privatdozentin Dr. Rita Dreier
• Subject Area: Orthopaedics, Traumatology, Reconstructive Surgery ; Cell Biology
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 402797071

• Final Report Year: 2023

Final Report Abstract

The most common joint disease worldwide, osteoarthritis (OA) is characterized by destruction of articular cartilage and damage to adjacent bones, muscles and ligaments. Joint stiffness and pain lead to a loss of quality of life in an increasing number of patients. Despite intensive research, no drugs are yet available to inhibit disease progression or reverse cartilage damage. The main risk factors for OA, age and obesity, are associated with endoplasmic reticulum stress (ER stress) in chondrocytes, which triggers a cellular rescue mechanism, the unfolded protein response (UPR). Depending on the level of stress, the UPR restores normal cell function or triggers apoptosis. In this research project, immunofluorescence and transmission electron microscopy in Crispr/Cas9-generated ERp57-KO-C28/I2 cells and cartilage-specific ERp57-KO mice (ERp57 cKO) showed that loss of the protein disulfide isomerase ERp57 was sufficient to induce ER stress in cartilage cells, allowing its association with OA and its function in cartilage to be analyzed. Under ER stress, 18-month-old animals developed marked OA with osteophyte formation in the knee joints. The cartilage changes were preceded by ER stress-induced apoptosis as well as decreased compressive stiffness of cartilage. In contrast, young ERp57 cKO were not susceptible to OA even when subjected to forced running on a treadmill. Thus, we conclude that ER stress plays a role in age-related knee osteoarthritis and less so in younger patients, as the protective function of the UPR in chondrocytes decreases with age, while apoptosis increases. Because gender effects are common in OA, we examined the response of male and female mice to ER stress. We observed a slower increase in agerelated ER stress and a lower number of apoptotic chondrocytes in female mice compared with males, which contributed to less severe OA in female mice. These results were supported in cell culture studies that showed a reduction in ER stress-induced apoptosis in C28/I2 cells in the presence of physiological estradiol concentrations. In conclusion, estradiol reduces ER stress-induced apoptosis in articular cartilage cells and decreases cartilage degeneration. Postmenopausal women lose this protective mechanism and therefore develop OA more rapidly. In summary, our results indicate that inhibition of ER stress is an attractive therapeutic target for OA. Selective estrogen receptor modulators or chemical chaperones such as 4-PBA, which we have shown to diffuse efficiently into cartilage explants and reduce excessive ER stress in chondrocytes in a dose-dependent manner, should be considered as therapeutic agents for OA and analyzed in depth.

Publications

• 4-Phenylbutyrate (4-PBA) reduces ER-Stress and inhibits autophagy in chondrocytes. Annual Meeting of the German Society for Matrix Biology 2018, Stuttgart
  Yvonne Knieper, Isabel Gronau, Uwe Hansen & Rita Dreier
  
• Cartilagespecific ERp57 knockout mice qualify as a novel model for the analysis of ER stressrelated skeletal diseases. Matrix biology Europe Meeting 2018, Manchester
  Yvonne Knieper, Isabel Gronau, Uwe Hansen, Markus Ramroth & Rita Dreier
  
• Different Forms of ER Stress in Chondrocytes Result in Short Stature Disorders and Degenerative Cartilage Diseases: New Insights by Cartilage‐Specific ERp57 Knockout Mice. Oxidative Medicine and Cellular Longevity, 2018(1).
  Rellmann, Yvonne & Dreier, Rita
  
• 4-Phenylbutyric Acid Reduces Endoplasmic Reticulum Stress in Chondrocytes That Is Caused by Loss of the Protein Disulfide Isomerase ERp57. Oxidative Medicine and Cellular Longevity, 2019, 1-12.
  Rellmann, Yvonne; Gronau, Isabel; Hansen, Uwe & Dreier, Rita
  
• Female ERp57 knock-out mice are less susceptible to ER stress, hypertrophic differentiation and apoptosis in chondrocytes. Annual Meeting of the German Society for Matrix Biology 2019, Regensburg
  Yvonne Rellmann, Markus Ramroth, Sandra Lukowski, Andrea Linz & Rita Dreier
  
• Knockout of the protein disulfide isomerase ERp57 results in reduced cartilage stiffness in the knee joint of male mice. Annual Meeting of the Dutch Society for Matrix Biology 2020, online
  Elco Eidhof, Y. Rellmann, M. Ramroth, L. Fleischhauer, H. Clausen-Schaumann & R. Dreier
  
• ER Stress in ERp57 Knockout Knee Joint Chondrocytes Induces Osteoarthritic Cartilage Degradation and Osteophyte Formation. International Journal of Molecular Sciences, 23(1), 182.
  Rellmann, Yvonne; Eidhof, Elco; Hansen, Uwe; Fleischhauer, Lutz; Vogel, Jonas; Clausen-Schaumann, Hauke; Aszodi, Attila & Dreier, Rita
  
• ERp57 directs extracellular matrix organization of the C28/I2 chondrocyte cell line. Annual Meeting of the German Society for Matrix Biology 2021, Frankfurt
  Elco Eidhof, Uwe Hansen & Rita Dreier
  
• Knockout of the protein disulfide isomerase ERp57 results in aggregation and retention of ECM proteins in chondrocytes. Annual Meeting of the German Society for Matrix Biology 2021, online
  Elco Eidhof, Y. Rellmann, L. Fleischhauer, H. Clausen-Schaumann & R. Dreier
  
• Loss of ERp57 in chondrocytes induces osteoarthritis in ageing mice. Annual Meeting of the German Society for Matrix Biology 2021, online
  Yvonne Rellmann, Markus Ramroth, Elco Eidhof, Uwe Hansen & Rita Dreier
  
• Review: ER stress-induced cell death in osteoarthritic cartilage. Cellular Signalling, 78, 109880.
  Rellmann, Yvonne; Eidhof, Elco & Dreier, Rita
  
• Estradiol inhibits endoplasmic reticulum stress-induced apoptosis in chondrocytes and reduces agerelated osteoarthritis. Matrix biology Europe Meeting 2022, Florenz
  Y. Rellmann, T. Ising, M. Ramroth, E. Eidhof, U. Hansen & R. Dreier
  
• Estradiol Inhibits ER Stress-Induced Apoptosis in Chondrocytes and Contributes to a Reduced Osteoarthritic Cartilage Degeneration in Female Mice. Frontiers in Cell and Developmental Biology, 10.
  Dreier, Rita; Ising, Thomas; Ramroth, Markus & Rellmann, Yvonne
  
• Missing protein disulfide isomerase ERp57 alters the extracellular matrix organization of cartilage. Annual Meeting of the Dutch Society for Matrix Biology 2022, Zeist
  E. Eidhof, U. Hansen & R. Dreier