Expression of high mobility group box chromosomal protein 1 and its modulating effects on downstream cytokines in systemic lupus erythematosus.
OBJECTIVE
To compare the expression of high mobility group box chromosomal protein 1 (HMGB1) and the modulating effects on its downstream cytokines in patients with systemic lupus erythematosus (SLE) and healthy controls.


METHODS
HMGB1 concentrations in serum from SLE patients and controls were measured by immunoblot analysis. HMGB1 messenger RNA (mRNA) expression in peripheral blood mononuclear cells (PBMC) was detected by real-time reverse transcription-polymerase chain reaction. Immunofluorescence assay was employed to examine the translocation of HMGB1 in monocytes after endotoxin stimulation. Release of tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6) by PBMC after rHMGB1 stimulation was also measured.


RESULTS
Serum HMGB1 levels and HMGB1 mRNA expressions in PBMC were elevated in SLE patients compared with controls. A positive correlation was demonstrated between HMGB1 concentrations and SLE Disease Activity Index. There was an inverse correlation between HMGB1 levels and C4 and C3 concentrations in SLE patients. HMGB1 concentrations were higher in patients with vasculitis and myositis. Lipopolysaccharide stimulated a temporarily elevated release of HMGB1 in SLE patients compared with controls. The pattern and localization of HMGB1 staining in monocytes were similar in both groups. After stimulation with rHMGB1, TNF-alpha level decreased but IL-6 level increased in SLE patients compared with controls.


CONCLUSIONS
Our findings suggest that increased serum levels of HMGB1 in SLE may be associated with lupus disease activity. The altered production of TNF-alpha and IL-6 in response to rHMGB1 stimulation may participate in the disruption of cytokine homeostasis in SLE.
Li
Jie
J
Department of Dermatology, Xiangya Hospital, Central South University, Hunan, China.
Xie
Hongfu
H
Wen
Ting
T
Liu
Hongbo
H
Zhu
Wu
W
Chen
Xiang
X
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015153:Blotting, Western; D002478:Cells, Cultured; D005260:Female; D005455:Fluorescent Antibody Technique; D024243:HMGB1 Protein / Q000097:blood* / Q000235:genetics; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000097:blood / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012720:Severity of Illness Index; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*
D024243:HMGB1 Protein; D015850:Interleukin-6; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha