Increased interleukin-22 levels in lupus nephritis and its associated with disease severity: a study in both patients and lupus-like mice model.

OBJECTIVES: Interleukin-22 (IL-22) has been considered as an inflammatory cytokine. In the present study, we investigated the potential role of IL-22 in lupus nephritis (LN). METHODS: We examined the IL-22 levels of serum and kidney tissue from LN patients and MRL/lpr mice. An intraperitoneal injection of saline, isotype control antibody (IgG), prednisone (3mg/kg/mouse), or anti-IL-22 mAb (5µg/kg/mouse or 25µg/kg/mouse) was administered twice a week from 6 to 18 weeks of age. RESULTS: IL-22 levels in both serum and kidney were significantly higher in LN patients as compared with those in healthy controls. The serum and renal levels of IL-22 in MRL/lpr mice were significantly increased over time. After MRL/lpr mice were treated with anti-IL-22 monoclonal antibody (mAb) for 12 weeks, significantly less urine protein and lower serum levels of creatinine and urea nitrogen were found. In addition, less renal injury score and few number of inflammatory cells per glomerulus were observed in MRL/lpr mice treated with anti-IL-22 mAb as compared with control groups. CONCLUSIONS: Our results suggest that IL-22 as a pathogenic cytokine might be a potential target for treatment of lupus nephritis.