Postmenopausal expression changes of immune system-related genes in human bone tissue.

Introduction: The molecular and cellular interactions between the immune system and bone tissue have been established. Sex hormone deficiency after menopause has multifunctional role by influencing growth, differentiation, and metabolism of the skeletal and the immune system.

Discussion: We have used nonparametric and multidimensional expression pattern analyses to determine significantly changed mRNA profile of immune system-associated genes in postmenopausal (POST) and premenopausal (PRE) nonosteoporotic bone. Ten bone tissue samples from POST patients and six bone tissue samples from PRE women were examined in our study. The transcription differences of the selected 50 genes were analyzed in TaqMan probe-based quantitative real-time reverse transcriptase polymerase chain reaction system. Mann-Whitney test indicated significantly downregulated transcription activity of three genes (CD14, HLA-A/MHCI, ITGAM/CD11b) and upregulated expression of six genes (C3, CD86/B7-2, IL-10, IL-6, TGFB3, TNFSF11/RANKL) in postmenopausal bone. According to the canonical variate analysis results, the groups of POST and PRE women are separable by genes coding for cytokines, costimulator molecules, and cell surface receptors involved in antigen presentation and T cell stimulation processes which have high discriminatory power. Based on a complex gene expression pattern analysis of human bone tissue, we could distinguish POST and PRE states from an immunological aspect. Our data might provide further insight into the changes of the intersystem crosstalk between immune and skeletal homeostasis, as well as local immune response in the altered microenvironment of postmenopausal bone.