Expression of HDAC2 in Peripheral Blood Mononuclear Cells from Patients with Sudden Sensorineural Hearing Loss

Abstract

Objectives: (1) Compare the expression of HDAC2 in peripheral blood mononuclear cells (PBMC) of refractory sudden sensorineural hearing loss (SSNHL) patients before and after intratympanic methylprednisolone perfusion (IMP). (2) Identify the relationship between the level of HDAC2 and the prognosis of patients. Methods: Twenty cases of refractory SSNHL patients were selected as therapy group and 10 volunteers were chosen as control group. All 20 SSNHL patients received one course of routine therapy or more, including GC, vasodilator, and neurotrophins. SSNHL patients-PBMCs were collected in the morning before and after IMP, while volunteers were collected on the second day in hospital from January 2013 to September 2013. After therapy, the 20 SSNHL patients were divided into 2 groups (GC sensitive group and GC insensitive group) according to their hearing recovery. Real-time polymerase chain reaction and HDAC2 Assay Kit were used to detect the expression level of HDAC2 mRNA and amount of HDAC2 protein in PBMCs. The data were analyzed with SPSS 17.0 software. Results: Before intratympanic methylprednisolone perfusion, the level of HDAC2 protein were significantly depressed in all SSNHL patients (F = 13.291,<.0001), while the HDAC2 mRNA expressing much higher than the control group (F = 6.047, =.007). The expression level of HDAC2 mRNA increased significantly after intratympanic methylprednisolone (GC sensitive group: t = 3.941, P = .006; GC insensitive group: t = 2.57, P = .026). The HDAC2 protein level in GC sensitive group increased significantly ( t = 6.148, P < .001). Conclusions: Knockdown of HDAC2 expression induces corticosteroid insensitivity. Glucocorticoids can increase the expression of HDAC2 mRNA. HDAC2 can be down-regulated by posttranslational modifications.