University of Oulu

Nieminen, P., Hämäläinen, W., Savinainen, J. et al. Metabolomics of Synovial Fluid and Infrapatellar Fat Pad in Patients with Osteoarthritis or Rheumatoid Arthritis. Inflammation 45, 1101–1117 (2022).

Metabolomics of synovial fluid and infrapatellar fat pad in patients with osteoarthritis or rheumatoid arthritis

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Author: Nieminen, Petteri1; Hämäläinen, Wilhelmiina2; Savinainen, Juha1;
Organizations: 1Institute of Biomedicine, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
2Department of Computer Science, Aalto University, P.O. Box 15400, 00076, Aalto, Finland
3School of Pharmacy/Pharmaceutical Chemistry, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
4Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, P.O. Box 5000, 90014, Oulu, Finland
5Department of Surgery and Medical Research Center, Oulu University Hospital, P.O. Box 21, 90029 OYS, Oulu, Finland
6Pohjola Hospital, Leväsentie 1, 70700, Kuopio, Finland
7Department of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital, P.O. Box 100, 70290 Kuopio, Finland
8Department of Environmental and Biological Sciences, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101, Joensuu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
Persistent link:
Language: English
Published: Springer Nature, 2022
Publish Date: 2022-09-19


Osteoarthritis (OA) and autoimmune-driven rheumatoid arthritis (RA) are inflammatory joint diseases with complex and insufficiently understood pathogeneses. Our objective was to characterize the metabolic fingerprints of synovial fluid (SF) and its adjacent infrapatellar fat pad (IFP) obtained during the same surgical operation from OA and RA knees. Non-targeted metabolite profiling was performed for 5 non-inflammatory trauma controls, 10 primary OA (pOA) patients, and 10 seropositive RA patients with high-resolution mass spectrometry-based techniques, and metabolites were matched with known metabolite identities. Groupwise differences in metabolic features were analyzed with the univariate Welch’s t-test and the multivariate linear discriminant analysis (LDA) and principal component analysis (PCA). Significant discrimination of metabolite profiles was discovered by LDA for both SF and IFP and by PCA for SF based on diagnosis. In addition to a few drug-derived substances, there were 16 and 13 identified metabolites with significant differences between the diagnoses in SF and IFP, respectively. The pathways downregulated in RA included androgen, bile acid, amino acid, and histamine metabolism, and those upregulated included biotin metabolism in pOA and purine metabolism in RA and pOA. The RA-induced downregulation of androgen and bile acid metabolism was observed for both SF and IFP. The levels of 11 lipid metabolites, mostly glycerophospholipids and fatty acid amides, were also altered by these inflammatory conditions. The identified metabolic pathways could be utilized in the future to deepen our understanding of the pathogeneses of OA and RA and to develop not only biomarkers for their early diagnosis but also therapeutic targets.

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Series: Inflammation
ISSN: 0360-3997
ISSN-E: 1573-2576
ISSN-L: 0360-3997
Volume: 45
Issue: 3
Pages: 1101 - 1117
DOI: 10.1007/s10753-021-01604-x
Type of Publication: A1 Journal article – refereed
Field of Science: 3121 General medicine, internal medicine and other clinical medicine
3126 Surgery, anesthesiology, intensive care, radiology
3111 Biomedicine
Funding: Open access funding provided by University of Eastern Finland (UEF) including Kuopio University Hospital. Financial support for the study was provided by the Academy of Finland (grant #322429 to PN). The funding source had no involvement in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.
Dataset Reference: The online version contains supplementary material available at
Copyright information: © The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit