Increased expression of the proprotein convertase enzyme FURIN in rheumatoid arthritis

Abstract

Objective: FURIN is a proprotein convertase enzyme that inhibits the proinflammatory function of T cells and myeloid cells. Elevated FURIN expression levels have been reported in immune-mediated diseases, such as primary Sjögren’s syndrome. Here, we investigated the levels of FURIN in peripheral blood (PB) and synovial fluid (SF) leucocytes from patients with rheumatoid arthritis (RA).

Method: FURIN mRNA expression in PB and SF cells was determined by quantitative reverse transcription–polymerase chain reaction and FURIN plasma levels were measured using enzyme-linked immunosorbent assay. Associations between FURIN levels and demographic and clinical characteristics of the patients were determined.

Results: FURIN levels were significantly elevated in PB and SF mononuclear cells, T cells, and monocytes from RA patients compared to healthy controls. High FURIN levels were significantly associated with the prevailing prednisolone treatment, higher prednisolone doses, and increased C-reactive protein levels and Health Assessment Questionnaire values.

Conclusion: FURIN is significantly upregulated in RA PB and SF leucocytes, suggesting that it may have a role in the pathogenesis of RA. In addition, our results suggest that elevated FURIN expression is associated with the indicators of more severe RA.

Acknowledgements

We thank Paula Kosonen, Merja Lehtinen, and Heidi Peussa for technical assistance.

This work was supported by the Academy of Finland (grant numbers 295814 and 286477), the Competitive State Research Financing of the Expert Responsibility area of Tampere University Hospital (grant numbers 9U047, 9V049, and 9M120), the Tampere Tuberculosis Foundation, the Sigrid Juselius Foundation, Jane and Aatos Erkko Foundation, the Finnish Cultural Foundation Pirkanmaa Regional fund, and the Cancer Society of Finland.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Academy of Finland [286477,295814];Jane ja Aatos Erkon Säätiö;Competitive State Research Financing of the Expert Responsibility area of Tampere University Hospital [9M120,9U047,9V049];Pirkanmaan Rahasto;Sigrid Juséliuksen Säätiö;Syöpäjärjestöt;Tampereen Tuberkuloosisäätiö;