Histone deacetylase-2 expression and activity in children with nephrotic syndrome with different glucocorticoid response.

BACKGROUND: Glucocorticosteroid (GC) is one of the most effective drugs available for the treatment of primary nephrotic syndrome (PNS) in children. However, some patients show little or no response to GC. The purpose of our research was to observe and describe the different levels of histone deacetylase-2 (HDAC2) expression in peripheral blood lymphocytes in children with PNS compared with various responses to the GC treatment, with the primary aim to assess the correlation between HDAC2 and GC resistance in PNS children.

METHODS: Forty-eight patients with PNS suffering from their first attack prior to GC treatment were chosen as subjects. They were divided into two groups, those who had steroid-sensitive nephrotic syndrome (SSNS; n = 25) and those with steroid-resistant NS (SRNS; n = 23), according to their response to a 6-week course of oral prednisone. Twenty healthy children from the Physical Examination Center in the hospital served as the control group; Peripheral blood was collected at different time points prior to GC treatment and after regular therapy. RT-PCR, western blot, and enzyme-linked immunosorbent assay (ELISA) techniques were adopted to analyze HDAC2 mRNA, protein expression, and activity, respectively, in peripheral blood lymphocytes. The level of interleukin-8 (IL-8) in serum was measured by an ELISA.

RESULTS: Prior to GC treatment, HDAC2 expression level and activity were lower in the SRNS group than in the SSNS and control group. A statistically significant difference in HDAC2 expression and activity were observed after GC treatment between these groups, with HDAC2 expression and activity lower in the SRNS group than in the SSNS and control groups. In the SSNS group, the expression and activity of HDAC2 were higher following GC treatment than prior to GC treatment. There was a clear difference in HDAC2 expression and activity of SRNS at the different time points. No statistically significant difference was found between the two groups. The pre-treatment and post-treatment serum IL-8 levels in the SRNS group were significantly higher than those in the SSNS group. HDAC2 from children with PNS before GC treatment and after regular therapy for 6 weeks was negatively correlated with serum IL-8 level.

CONCLUSION: The GC effect was influenced by the HDAC2 expression and activity, leading to decreased serum IL-8 levels in children with PNS. HDAC2 seems to be one of the markers of GC resistance in children with PNS.