Increased expression of c-rel, from the NF-kappaB/Rel family, in T cells from patients with systemic lupus erythematosus.
OBJECTIVE
To explore the role of the NF-kappaB/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-kappaB/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<0.00002) 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-kappaB/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 2 patients compared with 2 controls. Increased levels of both IkappaB alpha and IkappaB beta could account for c-Rel cytosolic retention.


CONCLUSIONS
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.
Burgos
P
P
Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile.
Metz
C
C
Bull
P
P
Pincheira
R
R
Massardo
L
L
Errázuriz
C
C
Bono
M R
MR
Jacobelli
S
S
González
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003208:Concanavalin A / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000737:chemistry / Q000378:metabolism*; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D016328:NF-kappa B / Q000096:biosynthesis* / Q000235:genetics; D020569:Proto-Oncogene Proteins c-rel / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000737:chemistry / Q000378:metabolism*
D007376:Interleukin-2; D016328:NF-kappa B; D020569:Proto-Oncogene Proteins c-rel; D012333:RNA, Messenger; D003208:Concanavalin A