IFN-alpha Downregulates ERK Phosphorylation of CD4+ T Lymphocytes in Systemic Lupus Erythematosus

Yoo, Wan Hee

Abstract

OBJECTIVE
CD4+ T cells from patients with systemic lupus erythematosus (SLE) display aberrant TCR signaling and IFN-alpha plays critical roles in the pathogenesis of SLE; however, the effects of IFN-alpha on disease-associated TCR signaling defects remain unknown. This study investigated the ERK phosphorylation during TCR triggering and the effects of IFN-alpha on ERK signaling in CD4+ T cells.
METHODS
CD4+ T lymphocytes were sorted from PBMC using magnetic beads in patients with SLE who met the 1982 revised ACR criteria for SLE and age-matched healthy controls. The phosphorylation of ERK 1/2 was analyzed by flow cytometry and mean fluorescent intensity was measured to define the degree of phosphorylation of ERK. In some experiments, anti-CD3 stimulation was performed after preincubation with patient or control serum, diluted in tissue culture media, with or without addition of an anti-IFN-alpha antibody. The serum level of IFN-alpha was measured by ELISA.
RESULTS
ERK-1/2 phosphorylation was decreased in CD4+ T cells of lupus patients than healthy controls and associated with disease activity. Pre-incubation of control CD4+ T cells with allogeneic lupus plasma decreased ERK-1/2 phosphorylation more than allogeneic control and RA plasma and this was reversed by anti-IFN-alpha Ab. Accordingly, ERK-1/2 phosphorylation was decreased in control CD4+ T cells pre-incubation with lupus plasma with high IFN-alpha levels more than lupus plasma with non-detectable IFN-alpha levels. Recombinant IFN-alpha inhibited TCR-mediated ERK-1/2 phosphorylation dose-dependently.
CONCLUSION
These results suggest that IFN-alpha stimulation in vivo may underlie the aberrant TCR-mediated MAPK signaling in lupus CD4+ T cells and associated with disease pathogenesis.