[The plasmic translocation and release of high mobility group box chromosomal protein 1 in peripheral blood monocytes of patients with rheumatoid arthritis and the effect of thalidomide].

OBJECTIVE: To investigate the release and intracellular localization of high mobility group box chromosomal protein 1 (HMGB1) in the peripheral blood monocytes of rheumatoid arthritis (RA) patients and the inhibitive effect of thalidomide. METHODS: 19 RA patients and 20 healthy controls were included in the study. Monocytes were separated from peripheral blood with Ficoll density gradient centrifugation. Monocytes were treated with 100 ng/ml tumor necrosis factor alpha (TNFalpha) or 100 ng/ml TNFalpha plus 40 microg/ml thalidomide and grown in an incubator at 37 degrees C with 5% CO2 for 24 hours. The culture supernatants of the monocytes were collected. HMGB1 level in the culture medium was detected with Western blot. In addition, the intracellular localization of HMGB1 in the monocytes was investigated with immunocytochemical analysis. RESULTS: Without stimulation, the release of HMGB1 protein was significantly increased in the culture supernatants of peripheral blood monocytes from RA patients as compared with that from healthy controls (P < 0.05). TNFalpha (100 ng/ml) did not further increase the release of HMGB1 in the monocytes from the patients with RA. Thalidomide (40 microg/ml) could inhibit the release of HMGB1 in the monocytes from RA patients stimulated with TNFalpha (P < 0.05). In the monocytes from RA patients, HMGB1 was mainly localized in the nucleus. Treatment with TNFalpha (100 ng/ml) for 24 hours resulted in a cytoplasmic translocation of HMGB1, which was inhibited significantly by thalidomide. CONCLUSION: TNFalpha induces the release and cytoplasmic translocation of HMGB1 in the peripheral blood monocytes of RA patients and thalidomide inhibits the release and translocation of HMGB1.

[Expression of high mobility group box chromosomal protein 1 in peripheral blood of patients with rheumatoid arthritis].

OBJECTIVE: To investigate the mRNA and protein expression of high mobility group box chromosomal protein 1 (HMGB1) in peripheral blood mononuclear cells (PBMCs) and serum. METHODS: Levels of HMGB1mRNA were detected with reverse transcription polymerase chain reaction (RT-PCR) in PBMC and levels of HMGB1 protein in PBMC and plasm were measured with Western blot in 38 patients with active rheumatoid arthritis (RA), 24 with inactive RA and 20 healthy controls. Ficoll density gradient centrifugation was used to separate PBMCs from peripheral blood. The correlation between the levels of HMGB1 in serum and the index of disease activity in RA was analyzed. RESULTS: There was no statistically significant difference of the mRNA expression of HMGB1 in PBMCs from active RA patients as compared with those from inactive RA group and healthy controls (F = 1.23, P > 0.05). The protein expression of HMGB1 was significantly lower in PBMCs from active RA patients (F = 70.91, P < 0.01), while the protein expression of HMGB1 was higher in plasma from active RA patients (P < 0.001) as compared with that from inactive RA patients and healthy controls. However, there was no statistically significant difference between inactive RA patients and healthy controls (P > 0.05). The level of HMGB1 protein in plasma of RA patients was correlated with erythrocyte sedimentation rate (ESR) (r(s) = 0.478, P < 0.001) and C- reactive protein (CRP) (r(s) = 0.574, P < 0.05). It was not correlated with age, the number of tender joints and swollen joints, radiographic scores and therapeutic effect. CONCLUSION: The protein expression of HMGB1 was significantly decreased in PBMCs from active RA patients, while it was increased in serum from active RA patients. HMGB1 plays a pivotal role in the pathogenesis of RA and may be a target of therapy as a novel cytokine.