Impaired function of PD-1+ follicular regulatory T cells in systemic
lupus erythematosus
Abstract
Aberrant autoantibody production is characteristic of systemic lupus
erythematosus (SLE), but follicular regulatory T (TFR) cells potentially
can suppress this abnormality. We investigate functional changes in TFR
cells from SLE patients. Circulating TFR cells were collected from 19
SLE patients and 14 healthy controls (HC) to compare molecular
expression and in vitro suppressive capacity of follicular helper T
(TFH) cell proliferation. To reveal the stability of Foxp3 in TFR,
pyrosequencing of conserved non-coding sequence (CNS) 2 at the Foxp3
gene locus was performed. We then tested IL-2 in SLE-TFR cells to check
restoration of suppressor function. Programmed death-1 (PD-1) expression
in SLE-TFR cells was positively correlated with anti-DNA antibody levels
and disease activity. These cells had impaired suppressive function for
TFH cells with decreased expression of suppression mediators forkhead
box p3 (Foxp3), cytotoxic T-lymphocyte antigen 4 (CTLA4), and IL-2
receptor alpha (IL2Rα). Pyrosequencing identified hyper-methylation in
CNS2 region of SLE-TFR cells comparing to HC. With In vitro IL-2
stimulation, PD-1 expression of TFR cells significantly decreased along
with increased expression of Foxp3 and CTLA-4, especially in low-dose.
Thus, SLE-TFR cells have functionally defective to TFH suppression, but
low-dose IL-2 therapy might be useful to restore this ability.