Olf1/EBF associated zinc finger protein interfered with antinuclear antibody production in patients with systemic lupus erythematosus.
BACKGROUND
The aim of the study was to determine whether Olf1/EBF associated zinc finger protein (OAZ), a transcription factor encoded by a positional systemic lupus erythematosus (SLE) candidate gene, plays a functional role in the pathogenesis in SLE.


METHODS
Gene expression levels in peripheral blood cells (PBLs) measured using quantitative real-time polymerase chain reaction (qPCR) were assessed for association with disease activity and the presence of specific autoantibodies. Peripheral blood mononuclear cells (PBMCs) were incubated with specific siRNAs for three days, then cells were harvested for measuring mRNA levels using qPCR, and supernatants for levels of total immunoglobulin (Ig)G and IgM as well as secreted cytokines, chemokine and antinuclear antibodies (ANA) using ELISA. Indirect immunofluorescence was also applied for ANA detection.


RESULTS
OAZ gene expressions in PBLs from 40 ANA-positive SLE patients were significantly increased than those from 30 normal controls (P < 0.0001) and 18 patients with rheumatoid arthritis (P < 0.01). In SLE patients, OAZ transcripts were positively correlated with SLE disease activity index (SLEDAI) score (r = 0.72, P < 0.0001) and higher in those positive for anti-dsDNA or anti-Sm antibodies (both P < 0.05). Co-culturing with OAZ siRNAs reduced mRNA levels of OAZ by 74.6 +/- 6.4% as compared to those co-cultured with non-targeting siRNA and OAZ silencing resulted in reduced total IgG, ANA, interferon (IFN)-gamma, interleukin (IL)-10, IL-12 and IL-21, but elevated CCL2 levels in culture supernatants (P < 0.05). The declined ANA levels correlated with inhibited OAZ expression (r = 0.88, P = 0.05), reduced IL-21 levels (r = 0.99, P < 0.01), and elevated chemokine (C-C motif) ligand 2 levels (r = -0.98, P < 0.01). Expressions of ID1-3 were significantly down-regulated by 68.7%, 70.2% and 67.7% respectively after OAZ silence, while ID3 was also highly expressed in SLE PBLs (P < 0.0001) and associated with disease activity (r = 0.76, P < 0.0001) as well as anti-dsDNA or anti-Sm antibodies (both P < 0.05).


CONCLUSIONS
Elevated expression of OAZ transcripts in SLE PBLs were strongly correlated with disease activity. Suppression of OAZ expression inhibited downstream ID levels, and secretion of ANA and IL-21, implicating a role of OAZ pathway in the pathogenesis of SLE.
Feng
Xuebing
X
Department of Rheumatology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, 210008, PR China. fengxuebing@hotmail.com
Li
Rongliang
R
Huang
Jing
J
Zhang
Huayong
H
Zhu
Lina
L
Hua
Bingzhu
B
Tsao
Betty P
BP
Sun
Lingyun
L
D000328:Adult; D000974:Antibodies, Antinuclear / Q000032:analysis / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000097:blood / Q000235:genetics*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis / Q000378:metabolism; D051798:Inhibitor of Differentiation Protein 1 / Q000235:genetics / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism*; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D011506:Proteins; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D012720:Severity of Illness Index
D000974:Antibodies, Antinuclear; D004268:DNA-Binding Proteins; C497453:ID1 protein, human; D007136:Immunoglobulins; D051798:Inhibitor of Differentiation Protein 1; D011506:Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C031017:ornithine decarboxylase antizyme