Introduction
Primary sjögren’s syndrome (pSS) is a typical autoimmune disorder
characterized by focal lymphocytic infiltrations, damage, and
dysfunction in salivary and lacrimal glands [1]. Lung, kidney, and
nervous system involvement could also occur in severe cases [2].
Previous studies have demonstrated the type I IFN signatures in
peripheral blood mononuclear cells (PBMCs), B cells, monocytes,
neutrophils as well as the affected tissues [3-10]. Moreover, IFN-α
inducible proteins: MDA-5, IFIT-3 [11], and B cell-activating factor
(BAFF) [12] were found highly expressed in salivary glands. Type I
IFN could enhance T cell and B cell responses and promote the production
of autoantibodies [11, 13], implicating their important roles in the
pathogenesis of pSS.
Acting as a premier type I IFN
producer and a key bridge between innate and adaptive immunity, pDCs
also play a nonnegligible contribution to autoimmune disease
development. pDCs in SLE patients can be activated through various
pathways (immune complexes, neutrophil extracellular traps,
mitochondrial DNA, etc .), which in turn trigger immune responses
and promote the production of autoantibodies [14]. In studies of
systemic sclerosis (SSc)
[15], Psoriasis [16], rheumatoid arthritis [17] and
autoimmune diabetes [18], pDCs could infiltrate into the target
tissue and exacerbate local inflammation by releasing IFN-α and
proinflammatory factors.
Currently, studies on the role of pDCs in pSS are limited. Previous
studies have reported the reduced frequencies of pDCs in peripheral
blood [19, 20] of pSS patients. A recent study performed a
transcriptional analysis of circulating pDCs and identified the aberrant
activation of pDC in pSS patients [21]. Here, we systematically
study the percentage, phenotype, and functions of pDCs for a better
understanding of their roles in the pathogenesis and type I IFN
signatures in pSS patients.