IgG4-related disease (IgG4-RD) is an immune-driven fibro-inflammatory disorder, affecting almost any tissue or organ and presenting as IgG4-related autoimmune pancreatitis (AIP), sclerosing cholangitis, sialoadenitis, dacryoadenitis, lung disease, tubulointerstitial nephritis and retroperitoneal fibrosis and so on. It is characterized by frequently elevated serum IgG4 levels and enlarged organs with pathologically massive lymphoplasmacytic infiltration and storiform fibrosis. T cells make up the bulk of lymphoplasmacytic cells and are considered to be crucial drivers of IgG4-RD. Abundant CD4+ and CD8+ T cells infiltrating the affected tissues have been detected in both animal models of AIP and patients with IgG4-RD.
Most studies focused extensively on CD4+ T cells in IgG4-RD. There are conflicting results of the polarization of T helper (Th)1 and Th2 cells. Initially, Th1- or Th2-type immune responses were indirectly reflected by elevated Th1 cytokines (IFN-γ) or Th2 cytokines (IL-4, IL-5 and IL-13) in serum or lesions. Subsequent researches detected directly the phenotypes of circulating Th1 and Th2 cells, and several studies reported elevated Th1 cells, whereas some results exhibited expanded Th2 cells. However, a recent study revealed the increases in both Th1 and Th2 cells and the synergistic effects of Th1- and Th2-type immune responses in IgG4-RD. Additionally, IgG4-RD is characterized by T cell polarization toward Th17 cells, releasing a proinflammatory cytokine IL-17. Moreover, recent studies demonstrate that numerous CD4+ cytotoxic T lymphocytes (CTLs) accumulate in peripheral blood and affected tissues of IgG4-RD, which not only can produce cytolytic molecules, but also secrete profibrotic cytokines IFN-γ, IL-1β and TGF-β1. However, limited data are available concerning CD8+ T cells in IgG4-RD. CD8+ CTLs with an activated phenotype aggregate in lesions and peripheral blood. In addition, expanded criculating T cytotoxic (Tc)1 subsets are examined, while Tc2 subsets have no significant changes. Given the importance of T cell responses, illustrating the features of T subsets is essential for in-deep understanding of the pathogenesis of IgG4-RD. However, the precise distribution patterns of CD4+ and CD8+ T cell subsets have not been systematically established in the entity.
Signaling lymphocytic activation molecule F7 (SLAMF7) is expressed on NK cells, NK T cells, CD8+, and CD4+ T cells, and plays important regulating roles in various immune responses. CD4+SLAMF7+ T cells increase and have potent cytolytic activity and profibrotic factors, such as IL-1β, IFN-γ and TGF-β1, which play an important role in the pathophysiology of IgG4-RD. Our previous study also shows the aberrant expansion of CD4+SLAMF7+ and CD8+SLAMF7+ T cells in experimental AIP. However, the expression and profiles of SLAMF7 on CD4+ and CD8+ T cell subsets have not been well studied in IgG4-RD.
In the present study, we characterized the distribution patterns and functional signatures of SLAMF7+ T cell subsets in patients with IgG4-RD.

Prompt: You are now acting as an expert in the field of immunology. From a professional point of view,  please polish the paragraph above to make it more logical, and academic