ASSOCIATION OF GLUCOCORTICOID RECEPTOR β EXPRESSION AND STEROID INSENSITIVITY IN PATIENTS WITH AUTOIMMUNE BULLOUS DISEASES

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Alternative splicing of the human glucocorticoid receptor (hGR) pre-mRNA generates two highly homologous isoforms, reserved hGR α and hGR β. In contrast to hGR α, hGRβ does not bind glucocorticoids and is transcriptionally inactive. Recently, hGRβ was suggested to play a role in glucocorticoid resistance because the expression of hGR β is increased in peripheral blood mononuclear cells (PBMCs) in patients with fatal asthma and glucocorticoid-resistant ulcerative colitis. Our previous study demonstrate that the expression of hGR β is significantly lower tha that of hGR α in PBMC from normal volunteers as revealed by semiquantitative RT-PCR and immunohistochemistry. The aim of this study was to clarify whether analysis of hGR α and hGR β can predict the response to glucocorticoids in patients with autoimmune bullous diseases. Total RNA obtained from peripheral blood mononuclear cells (PBMCs) of 5 patients with pemphigus or bullous pemphigoid and 7 healthy volunteers was analysed by semiquantitative RT-PCR and one-step RT-PCR using specific TaqMan probe for hGR α and β. Semiquantitative RT-PCR revealed that the expression of hGR β is significantly lower than that of hGR α in PBMC both in patients with BP and healthy volunteers. However, in contrast to the results obtained from semiquantitative RT-PCR, the real time PCR could not demonstrate quantitative difference of expression level of both hGR α and hGR β. The second experiment with various concentration of primers specific for both hGR α and hGR β showed that relative ratio of hGR α and hGR β mRNA expression could fluctuate according to the primer concentration. The third experiment using another new primers and a TaqMan probe specific for hGR α and hGR β also failed to establish the optimal conditions for quantitative analysis of hGR α and hGR β.