Abstract

OBJECTIVE:

We studied the role of type 17 Th cells (TH17) in the pathogenesis of SLE.

METHODS:

We quantified the mRNA expression of IL-17, -23, -27 and retinoic-acid-related orphan receptor (ROR)-gamma, the regulator for the development and function of TH17, in the urinary sediment of 23 subjects with active lupus nephritis, 25 subjects with a history of lupus nephritis in remission, 30 SLE patients with no history of renal involvement and 8 healthy subjects.

RESULTS:

All three groups of lupus patients had a higher urinary expression of TH17-related cytokines than the controls. However, urinary expression of IL-17 and -27 was found to be inversely correlated with the SLEDAI score (r = -0.252 and -0.258, respectively; P < 0.05 for both). For patients with active lupus nephritis, the histological activity index of kidney biopsy was also found to be inversely correlated with the urinary expression of ROR-gamma (r = -0.447; P = 0.032), IL-17 (r = -0.454; P = 0.029) and IL-23 (r = -0.455; P = 0.029). Urinary expression of IL-17, -23, -27 and ROR was also found to be inversely correlated with the urinary expression of IFN-gamma and T-bet, the key transcription factor of type 1 Th cells. After 6 months of treatment, urinary IL-27 expression rose significantly in patients with complete response (from 2.07 +/- 1.62 to 3.70 +/- 1.69; P = 0.028) but remained unchanged in those with partial or no response (from 2.60 +/- 1.87 to 2.52 +/- 1.94; P = 0.9).

CONCLUSIONS:

The urinary expression of TH17-related genes is increased in SLE patients. The degree of up-regulation, however, is inversely related to systemic and renal lupus activity, as well as urinary expression of TH1-related genes. Urinary expression of TH17-related genes increased again after successful immunosuppressive treatment of active disease. Our findings suggest a regulatory role of TH17-related cytokines in pathogenesis of lupus nephritis.