Evidence map›Paper›PMID 40450162›Full record

ArticleClinical rheumatology2025

Synovial fluid o-tyrosine is a potential biomarker for autoimmune-driven rheumatoid arthritis.

Anne-Mari Mustonen, Juha Savinainen, Marko Lehtonen, Petri Lehenkari, Tommi Kääriäinen, Antti Joukainen, Heikki Kröger, Petteri Nieminen

Abstract read
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In one paragraph

Article in Clinical rheumatology, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.

0numbers the graph read from it
0cells of the map it votes in
4citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

4 citing papers in PubMed.

  1. Review
  2. Calpain inhibition by calpeptin modulates adipocyte lipid metabolism and secretome-mediated inflammatory crosstalk with hepatocytes.Inflammation research : official journal of the European Histamine Research Society ... [et al.] · 2026
    Article
  3. Review
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Anne-Mari MustonenInstitute of Biomedicine, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland. anne-mari.mustonen@uef.fi.ORCID http://orcid.org/0000-0003-2266-2518
Juha SavinainenInstitute of Biomedicine, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
Marko LehtonenSchool of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
Petri LehenkariTranslational Medicine Research Unit, Faculty of Medicine, University of Oulu, Oulu, Finland.
Tommi Kääriäinen, Pihlajalinna, Kuopio, Finland.
Antti Joukainen, Pihlajalinna, Kuopio, Finland.
Heikki KrögerDepartment of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital, Kuopio, Finland.
Petteri NieminenInstitute of Biomedicine, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

INTRODUCTION/

objectivesThe aim of the present study was to identify key amino acid (AA) pathways in osteoarthritis (OA) and autoimmune-driven rheumatoid arthritis (RA), as AAs have emerged as potential biomarkers for the detection of degenerative joint diseases. It was hypothesized that we would detect distinct metabolic pathways activated in OA and RA due to different degrees of inflammation.

methodSamples of synovial fluid (SF) and infrapatellar Hoffa's fat pad (IFP) were collected from end-stage knee OA (n = 10) and RA patients (n = 10), and from non-inflammatory controls (n = 5). Metabolites were analyzed utilizing a liquid chromatography high-resolution mass spectrometry approach, followed by univariate and multivariate statistical testing and pathway analysis by MetaboAnalyst. Receiver operating characteristic analysis was used to examine diagnostic values.

resultsSF results identified o-tyrosine as a promising biomarker for distinguishing RA patients from OA patients and controls, and cystine, cysteine, and methionine separating OA patients from controls. Regarding IFPs, β-alanine could have diagnostic value to discriminate RA and OA. The present data indicate alterations in metabolic pathways, such as cysteine and methionine metabolism in RA and OA SFs compared to control SF, selenocompound metabolism in RA vs. OA SFs, and pyrimidine metabolism in RA vs. OA IFPs.

conclusionsThe identified nitrogen compounds, particularly o-tyrosine, and AA metabolism pathways have potential as novel diagnostic and therapeutic targets for degenerative joint diseases. Key Points • Synovial fluid o-tyrosine can distinguish rheumatoid arthritis from osteoarthritis and control. • Synovial fluid cystine, cysteine, and methionine separate osteoarthritis from control. • β-Alanine in intra-articular fat has diagnostic value between rheumatoid arthritis and osteoarthritis. • A routine measurement of o-tyrosine would be useful in the future as an indicator of rheumatoid arthritis.

Indexed as

Arthritis, RheumatoidOsteoarthritis, KneeSynovial FluidTyrosineAdultAgedBiomarkersCase-Control StudiesFemaleHumansMaleMiddle AgedBiomarkersTyrosineAmino acidInfrapatellar fat padOsteoarthritisRheumatoid arthritisSynovial fluid

Identifiers

PMID40450162
PMCPMC12234615

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.