Increased expression of c-<i>rel</i>, from the NF-κB/Rel family, in T cells from patients with systemic lupus erythematosus
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Date
2000
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Abstract
Objective. To explore the role of the NF-kappa B/Rel transcription factor family in autoimmunity, we investigated whether peripheral blood mononuclear cells (PBMC) and T cells from the blood of patients with systemic lupus erythematosus (SLE) exhibit abnormal expression of c-rel, both when recently isolated and/or during in vitro activation.
Methods. Total RNA and protein extracts were prepared from PBMC and T cells isolated by immunoadsorption with magnetic beads. The relative concentrations of c-rel mRNA and of c-Rel protein were determined by semiquantitative assays of competitive reverse transcriptase-polymerase chain reaction and chemiluminescent immunoblots, respectively. Activity of NF-kappa B/Rel was studied by electrophoretic mobility shift assay of nuclear extracts.
Results, Significantly increased levels of c-rel mRNA were found (1) in PBMC from SLE patients (n = 48; p < 0.0000001), even during inactive disease (n = 11; p < 0.001), compared to controls (n = 54), and (2) in T cells isolated from a subgroup of these: patients (n = 11; p < 0.00003) and controls (n = 12). c-Rel protein was found increased in the cytosol but not in the nucleus of PBMC of patients with SLE (n = 12; p < 0.02) compared to controls (n = 12). No evidence of NF-kappa B/Rel nuclear activity was detected. In vitro stimulation of T cells by incubating PBMC with concanavalin A showed that less c-Rel entered the nucleus in lupus cells than healthy cells, correlating with lower interleukin 2 production. However, the same stimulating conditions provoked an increase in c-rel mRNA to higher levels in lupus cells from 3 patients compared with 2 controls. Increased levels of both I kappa B alpha and I kappa B beta could account for c-Rel cytosolic retention.
Conclusion. Our data suggest that T cells from patients with SLE possess altered regulatory mechanisms of c-rel expression and nuclear import that might potentially determine conditions for developing autoimmunity. Other cells present in the PBMC could also be affected.
Methods. Total RNA and protein extracts were prepared from PBMC and T cells isolated by immunoadsorption with magnetic beads. The relative concentrations of c-rel mRNA and of c-Rel protein were determined by semiquantitative assays of competitive reverse transcriptase-polymerase chain reaction and chemiluminescent immunoblots, respectively. Activity of NF-kappa B/Rel was studied by electrophoretic mobility shift assay of nuclear extracts.
Results, Significantly increased levels of c-rel mRNA were found (1) in PBMC from SLE patients (n = 48; p < 0.0000001), even during inactive disease (n = 11; p < 0.001), compared to controls (n = 54), and (2) in T cells isolated from a subgroup of these: patients (n = 11; p < 0.00003) and controls (n = 12). c-Rel protein was found increased in the cytosol but not in the nucleus of PBMC of patients with SLE (n = 12; p < 0.02) compared to controls (n = 12). No evidence of NF-kappa B/Rel nuclear activity was detected. In vitro stimulation of T cells by incubating PBMC with concanavalin A showed that less c-Rel entered the nucleus in lupus cells than healthy cells, correlating with lower interleukin 2 production. However, the same stimulating conditions provoked an increase in c-rel mRNA to higher levels in lupus cells from 3 patients compared with 2 controls. Increased levels of both I kappa B alpha and I kappa B beta could account for c-Rel cytosolic retention.
Conclusion. Our data suggest that T cells from patients with SLE possess altered regulatory mechanisms of c-rel expression and nuclear import that might potentially determine conditions for developing autoimmunity. Other cells present in the PBMC could also be affected.
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NF-kappa B/Rel, c-rel, autoimmunity, systemic lupus erythematosus