Overexpression of A3 adenosine receptor in peripheral blood mononuclear cells in rheumatoid arthritis: involvement of nuclear factor-kappaB in mediating receptor level.
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-kappaB (NF-kappaB), a transcription factor present in the A3AR promoter, in mediating receptor upregulation.


METHODS
A3AR and NF-kappaB protein levels were evaluated in PBMC of RA patients (n = 23) and healthy subjects by Western blot. A3AR and NF-kappaB 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-alpha (TNF-alpha). 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-kappaB. Similar findings were observed in PHA and LPS-stimulated PBMC from healthy subjects. Antibodies against IL-2 or TNF-alpha prevented the increase in A3AR and NF-kappaB expression.


CONCLUSIONS
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-kappaB.
Madi
Lea
L
Can-Fite BioPharma Ltd., Kiryat-Matalon, Petah-Tikva, Israel.
Cohen
Shira
S
Ochayin
Avivit
A
Bar-Yehuda
Sara
S
Barer
Faina
F
Fishman
Pnina
P
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000037:antagonists & inhibitors; D007963:Leukocytes, Mononuclear / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D008934:Mitogens / Q000502:physiology; D016328:NF-kappa B / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D043684:Receptor, Adenosine A3 / Q000097:blood* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors
D007376:Interleukin-2; D008934:Mitogens; D016328:NF-kappa B; D043684:Receptor, Adenosine A3; D014409:Tumor Necrosis Factor-alpha; C084956:N(6)-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine; D000241:Adenosine