Imbalance between interleukin-6 and adrenomedullin mRNA levels in peripheral blood mononuclear cells of patients with lupus nephritis

In this study, we measured the mRNA levels of adrenomedullin (AM), C-type n atriuretic peptide, vascular endothelial growth factor, interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) in peripheral blood mononuclear cells (PBMC) of 34 patients with lupus nephritis (LN) (15 active and 19 inactive) and 30 healthy volunteers. mRNA levels were measured using a real-time qua ntitative PCR method. Compared with healthy volunteers, IL-6 mRNA levels we re elevated in LN patients (P < 0.005), while AM mRNA levels were decreased (P < 0.05). Also, IL-6 mRNA levels were higher and AM mRNA levels lower in active LN patients compared with inactive LN patients. In addition, IL-6 m RNA levels positively correlated and AM mRNA levels negatively correlated w ith SLE disease activity index and laboratory findings, such as blood urea nitrogen, serum creatinine, 50% haemolytic unit of complement and urinary e xcretion of protein over 24 h. Furthermore, IL-6 mRNA levels were negativel y correlated with AM mRNA levels within the same LN patients. With regard t o pathological findings, our results showed that IL-6 mRNA levels were high er, and AM mRNA levels significantly lower in patients with a high activity index compared to those with a low activity index. Following treatment wit h prednisolone, IL-6 mRNA levels in active LN patients decreased and AM mRN A levels increased to levels comparable to those in inactive LN and healthy volunteers. In vitro studies further demonstrated that elevated IL-6 mRNA levels in active LN patient PBMC were suppressed by the addition of adrenom edullin. Our results suggest that an imbalance between IL-6 and AM levels m ay play an important role in the progression of SLE, and that the mRNA leve ls of these genes in PBMC may be used as a disease activity index for SLE.