IntroductionImmunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a new disease entity characterized by high serum IgG4 levels, IgG4-positive plasmacytic infiltration, and fibrosis in various organs. The purpose of this study was to determine the mechanism of upregulation of IgG4 class switch recombination in IgG4-RD.MethodsWe extracted RNA from peripheral blood mononuclear cells (PBMCs) of patients with IgG4-RD (n = 6), Sjögren syndrome (SS) (n = 6), and healthy controls (n = 8), from CD3-positive T cells and CD20-positive B cells sorted from PBMCs of patients with IgG4-RD (n = 3), SS (n = 4), and healthy controls (n = 4), as well as from labial salivary glands (LSGs) of patients with IgG4-RD (n = 11), SS (n = 13), and healthy controls (n = 3). The mRNA expression levels of IgG4-specific class switch-related molecules, such as Th2 cytokines (IL-4 and IL-13), Treg cytokines (IL-10 and TGF-β), and transcriptional factors (GATA3 and Foxp3) were examined with quantitative polymerase chain reaction (PCR). IgG4-nonspecific class switch-related molecules, such as CD40, CD154, BAFF, APRIL, IRF4, and AID, were also examined.ResultsThe expression levels of Treg cytokines (IL-10 and TGF-β) and AID were significantly higher in LSGs of IgG4-RD than in SS and the controls (P < 0.05, each). In contrast, those of CD40 and CD154 were significantly lower in PBMCs of IgG4-RD than in SS (P < 0.05, each), whereas CD40 in CD20-positive B cells and CD154 in CD3-positive T cells were comparable in the three groups.ConclusionOverexpression of IL-10, TGF-β, and AID in LSGs might play important roles in the pathogenesis of IgG4-RD, such as IgG4-specific class-switch recombination and fibrosis. IgG4 class-switch recombination seems to be mainly upregulated in affected organs.
IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS) is characterized by bilateral swelling of glandular tissues with extensive fibrosis, and is immunologically considered a Th2-predominant disease. Recent studies reported that alternatively activated (M2) macrophages enhanced Th2 immune responses and fibrosis by production of pro-fibrotic factors (IL-10, IL-13 and CCL18). Therefore, we examined the association between M2 macrophages and fibrosis in submandibular glands from 7 patients with IgG4-DS, 10 patients with chronic sialoadenitis, 10 patients with Sjögren's syndrome, and 10 healthy subjects. The number of M2 macrophages in SMGs from patients with IgG4-DS was also significantly higher than in the other groups. Double immunofluorescence staining showed that IL-10 and CCL18 expression co-localized with M2 macrophage-marker (CD163). Furthermore, the SMG fibrosis score was positively correlated with the frequency of M2 macrophages in only IgG4-DS. These results indicate that IL-10 and CCL18 secreted by preferential M2 macrophages possibly play a key role in the development of severe fibrosis in IgG4-DS.
Rheumatoid arthritis (RA) is an autoimmune disorder characterized by chronic inflammation of the joint synovium and infiltration by activated inflammatory cells. CD4+ T cells form a large proportion of the inflammatory cells invading the synovial tissue, and are involved in the RA pathologic process. In general, CD4+ T cells differentiate into various T helper cell subsets and acquire the functional properties to respond to specific pathogens, and also mediate some autoimmune disorders such as RA. Because the differentiation of T helper cell subsets is determined by the expression of specific transcription factors in response to the cytokine environment, these transcription factors are considered to have a role in the pathology of RA. Treg cells control an excess of T cell–mediated immune response, and the transcription factor FoxP3 is critical for the differentiation and function of Treg cells. Treg cell dysfunction can result in the development of systemic autoimmunity. In this review, we summarize how the expression of transcription factors modulates T helper cell immune responses and the development of autoimmune diseases, especially in RA. Understanding the role of transcription factors in the pathogenesis of autoimmunity may lead to novel therapeutic strategies to control the differentiation and function of both T helper cells and Treg cells.
IgG4-related disease (IgG4-RD) is characterized by elevated serum IgG4 and marked infiltration of IgG4-positive cells in multiple organs. Interleukin-33 (IL-33) is a recently described cytokine that is secreted by damaged epithelial cells, macrophages, and dendritic cells, and potently activates helper T type 2 (Th2) immune responses, which have been suggested to play a major role in IgG4 production of IgG4-RD. Here, we assessed the expression of IL-33 and related molecules in the salivary glands (SGs) of patients with IgG4-RD versus that in patients with Sjögren’s syndrome (SS) and controls. Expression of IL-33 and its receptor (ST2) was strongly detected around ectopic germinal centers (GCs) in the SGs from patients with IgG4-RD, whereas IL-33 was expressed only in epithelial cells in patients with SS and controls. Moreover, IL-33 and CD68+/CD163+ macrophages were mainly distributed around ectopic GCs in patients with IgG4-RD. Double immunofluorescence staining showed that IL-33 expression co-localized with CD68+/CD163+ macrophages. Finally, mRNA expression levels of IL-33 showed a positive correlation to those of Th2 cytokines (IL-4 and IL-13) in patients with IgG4-RD. Our data suggest that IL-33 produced by M2 macrophages might contribute to the pathogenesis of IgG4-RD via aberrant activation of Th2 immune responses.
The 2010-2011 nationwide survey of ASD identified important changes in treatment and improvement of prognosis compared with previous surveys.
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