Emerging role of IL-17 and Th17 cells in systemic lupus erythematosus

Increased Th17 cells in flow cytometer-sorted CD45RO-positive memory CD4 T cells from patients with systemic lupus erythematosus

Objectives

Th17/IL-17 dysregulation is involved in human autoimmunity, and recent evidence suggests the character of long-lived differentiated memory cells in Th17. By directly measuring the peripheral blood mononuclear cells (PBMC), elevated circulating frequencies of Th17 cells have been reported in systemic lupus erythematosus (SLE) with inconsistent results regarding the correlation with disease activities. In this study, the association between circulating Th17 frequencies and disease activities or laboratory parameters was examined in flow cytometer-sorted CD45RO-positive memory CD4 T cells from SLE.

Methods

PBMC samples were obtained from 48 female lupus patients and another 48 age- and sex-matched healthy individuals. We examined frequencies of Th17 cells by sorting the purified CD4 T cells bearing the CD45RO marker, followed by intracellular IL-17A staining after in vitro activation. Frequencies of Th1 and T_Foxp3 cells were also measured by intracellular IFN-γ and Foxp3 staining, respectively. The SLE disease activity index (SLEDAI) and other laboratory parameters were further correlated with frequencies of different T cell subsets.

Results

In SLE, increased frequencies of Th17 cells were found with a positive correlation in SLEDAI. Higher frequencies of Th17 cells were found in lupus nephritis. There was a positive correlation between frequencies of Th17 cells and daily proteinuria amount.

Conclusions

By examining the sorted CD45RO-positive memory CD4 T cells, we confirm the dysregulation of Th17/IL-17 in SLE, implicating the potential to treat lupus patients with selective IL-17/IL-17R blockades.

Prevention of immune nephritis by the small molecular weight immunomodulator iguratimod in MRL/lpr mice

OBJECTIVE

This study was performed to investigate the therapeutic effects of iguratimod in a lupus mouse model.

METHODS

Female MRL/lpr mice were treated with iguratimod, vehicle solution or cyclophosphamide. Proteinuria was monitored and kidney injury was blindly scored by a renal pathologist. Serum anti-double-stranded DNA antibodies were monitored by radioimmunoassay. Kidney IgG and CD20 were stained by immunohistochemistry. Splenic lymphocyte phenotypes were analyzed by flow cytometry. BAFF, IL-17A, IL-6, and IL-21 levels in serum and splenic lymphocytes were detected by ELISA or quantitative PCR.

RESULTS

Compared with the vehicle-treated controls, MRL/lpr mice treated with iguratimod showed less protenuria, less acute pathological lesions and no chronic changes in the kidneys. There were significant differences in glomerular injury and vasculitis scores, as well as in the semi-quantitative analysis of immune complex deposition between the two groups. Disease activity markers in sera (anti-dsDNA antibodies and immunoglobulin levels) were reduced and hypocomplementemia was attenuated. Lymphocyte expression of BAFF, IL-6, IL-17A and IL-21 was decreased. The abnormal splenic B220+ T cell and plasma cell populations in MRL/lpr mice were reduced by iguratimod treatment, with recovery of the total B cell population and inhibition of B cell infiltration of the kidney tissue. The dosage of iguratimod used in this study showed no significant cytotoxic effects in vivo and no overt side-effects were observed.

CONCLUSION

Iguratimod ameliorates immune nephritis in MRL/lpr mice via a non-antiproliferative mechanism. Our data suggest a potential therapeutic role of iguratimod in lupus.