Osteopontin and osteoclasts in rheumatoid arthritis and osteoarthritis.

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Leena Palotie auditorium (101A), Faculty of Medicine, University of Oulu, Aapistie 5 A, Oulu

Topic of the dissertation

Osteopontin and osteoclasts in rheumatoid arthritis and osteoarthritis.

Doctoral candidate

Licentiate of Medicine Jani Luukkonen

Faculty and unit

University of Oulu Graduate School, Faculty of Medicine, Cancer Research and Translational Medicine Research Unit

Subject of study



Professor Timothy Arnett, University College London, UCL


Professor Petri Lehenkari, University of Oulu

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Osteoclast function and factors that affect them in osteoarthritis and rheumatoid arthritis

In this thesis, it is shown that the osteoclasts’, the bone resorbing cells, function and the factors that affect them, especially protein osteopontin, change in osteoarthritis and rheumatoid arthritis.

Rheumatoid arthritis and osteoarthritis are two chronic joint diseases, which cause two of the largest socioeconomic burdens among all joint diseases according to the World Health Organization. The etiology or pathogenesis of these diseases are not completely understood. Traditionally, osteoarthritis is seen as a disease resulting from mechanical wear of cartilage and bone, and rheumatoid arthritis as an inflammatory disease of synovial tissue.

The factors that affect osteoclasts were studied from osteoarthritis and rheumatoid arthritis patient samples. Osteoclast function was studied in cell cultures. Real patient samples were used in the cell cultures to mimic the real pathological environment.

The most important discoveries were: the phosphorylation of osteopontin is increased in rheumatoid arthritis synovial fluid, osteoclasts secrete osteopontin into the resorbed area during bone resorption, and how the use of different patient samples significantly affected osteoclast differentiation, due to so-called inflammatory osteoclastogenesis.

These new discoveries are yet to show their clinical significance, but we hope that in future they may reveal even new therapeutic possibilities.
Last updated: 1.3.2023