Autoantibodies against interferon-γ reduce the frequency of pulmonary fibrosis and concentration of C-reactive protein in patients with primary Sjögren's syndrome

Abstract

Primary Sjögren's syndrome (pSS) is a prototypic autoimmune disease characterized by immune injury to the salivary and lacrimal glands. In addition, some patients with pSS develop several systemic complications, such as renal, pulmonary or neurological manifestations. The establishment of type I interferons (IFN) pathway designates pSS an autoimmune disease characterized by an “IFN-signature” [1], but type II IFN, IFN-γ, also participates in the pathogenesis of pSS. Expression of high levels of IFN-γ mRNA and serum IFN-γ is found in conjunctiva and labial salivary glands in patients with pSS and correlates with degree of T-cell infiltration [2–4]. In animal models, high levels of IFN-γ can be detected in NOD/ShiLtJ and NOD-derived congenic C57BL/6.NOD-Aec1Aec2 mice newborned [5,6]. High production of IFN-γ was also found in muscarinic type 3 receptor−/− (M3R−/−) mice treated with free-form extracellular peptides of M3R [7]. IFN-γ-producing M3R-reactive T cells play a crucial role in the generation of SS-like sialadenitis via the induction of apoptosis [8]. However, few studies have been performed on the anti-IFN-γ autoantibodies (aAbs) in patients with pSS.