Overexpression of A₃ Adenosine Receptor in Peripheral Blood Mononuclear Cells in Rheumatoid Arthritis: Involvement of Nuclear Factor-kB in Mediating Receptor Level

LEA MADI, SHIRA COHEN, AVIVIT OCHAYIN, SARA BAR-YEHUDA, FAINA BARER, and PNINA FISHMAN

ABSTRACT.

Objective. A₃ adenosine receptor (A₃AR) upregulation has been found in cells of synovial tissue and in peripheral blood mononuclear cells (PBMC) of rats with adjuvant-induced arthritis. We investigated A₃AR levels in PBMC of patients with rheumatoid arthritis (RA) and in mitogen-activated PBMC from healthy subjects. We examined the role of nuclear factor-kB (NF-kB), a transcription factor present in the A₃AR promoter, in mediating receptor upregulation.

Methods. A₃AR and NF-kB protein levels were evaluated in PBMC of RA patients (n = 23) and healthy subjects by Western blot. A₃AR and NF-kB levels were also analyzed in phytohemagglutinin (PHA) and lipopolysaccharide (LPS)-stimulated PBMC in the presence and absence of antibodies against interleukin 2 (IL-2) and tumor necrosis factor-a (TNF-a). Reverse transcription-polymerase chain reaction was performed in PHA-stimulated PBMC of healthy subjects to determine A₃AR expression.

Results. A₃AR was overexpressed in PBMC of RA patients compared to healthy subjects and was directly correlated to an increase in NF-kB. Similar findings were observed in PHA and LPS-stimulated PBMC from healthy subjects. Antibodies against IL-2 or TNF-a prevented the increase in A₃AR and NF-kB expression.

Conclusion. Overexpression of A₃AR was found in PBMC of RA patients. Receptor upregulation was induced by inflammatory cytokines controlling the expression of the A₃AR transcription factor NF-kB. (J Rheumatol 2007;34:20–6)

Key Indexing Terms:

A₃ ADENOSINE RECEPTOR
RHEUMATOID ARTHRITIS
NUCLEAR FACTOR-kB
IB-MECA
PHYTOHEMAGGLUTININ
LIPOPOLYSACCHARIDE

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From Can-Fite BioPharma Ltd., Kiryat-Matalon, Petah-Tikva; and The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.

L. Madi, PhD; S. Bar-Yehuda, PhD; F. Barer, PhD, Can-Fite BioPharma Ltd.; S. Cohen, BSc; A. Ochayin, MSc; P. Fishman, PhD, Can-Fite BioPharma Ltd. and Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University.

Address reprint requests to Dr. P. Fishman, Can-Fite BioPharma, 10 Bareket Street, PO Box 7537, Petach-Tikva 49170, Israel. E-mail: pnina@canfite.co.il

Accepted for publication September 11, 2006.

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