Cupic Barbara, Breljak Davorka, Gabrilovac Jelka
Rudjer Boskovic Institute, Division of Molecular Medicine, Laboratory for Experimental Hematology, Immunology and Oncology, HR-10 002 Zagreb, Croatia.
Int J Mol Med. 2005 Jun;15(6):1023-31.
Neutral endopeptidase is a membrane bound enzyme with various functions depending on cell type or tissue origin. Normal development and differentiation of immature B lymphocytes depends on expression of CD10/NEP on B cell progenitors and bone marrow stromal cells. Synthetic glucocorticoid dexamethasone (dex), an immunosuppressive and anti-inflammatory drug, was shown to be a potent modulator of CD10/NEP expressed on cells of non-hematopoietic origin. We investigated the effect of dex on expression of differentiation marker CD10/NEP on immature B cells. The drug was applied in concentrations corresponding to the physiological range. CD10/NEP was measured at three levels of expression: mRNA (by means of duplex PCR), membrane protein marker (FACS analysis) and enzyme activity (hydrolysis of a selective chromogenic substrate). Dex down-regulated CD10/NEP expression on immature B cell line NALM-6 in a concentration- and time-dependent fashion. The effect was detected at all three levels. Dex-induced CD10/NEP down-regulation was mediated via glucocorticoid receptors (GR), as it was fully abrogated by a GR antagonist, RU 38486. That occurred at all three levels. The mechanism of dex-induced CD10/NEP down-regulation is not likely to include selection of cells that are CD10low since the effect was partly reversible after the removal of dex. However, dex-induced CD10/NEP down-regulation did include decreased transcription of the CD10 mRNA. Transcriptional inhibitor actinomycin D completely abolished dex-induced CD10/NEP down-regulation. Since differentiation of normal B lymphocytes is associated with down-regulation of CD10/NEP, the data presented suggest that low, physiologically relevant concentrations of glucocorticoids (such as observed in acute stress) may play a regulatory role in normal development and maturation of B lymphocytes.
中性内肽酶是一种膜结合酶，其功能因细胞类型或组织来源而异。未成熟B淋巴细胞的正常发育和分化取决于B细胞祖细胞和骨髓基质细胞上CD10/NEP的表达。合成糖皮质激素地塞米松（dex）是一种免疫抑制和抗炎药物，已被证明是一种有效的非造血来源细胞上表达的CD10/NEP调节剂。我们研究了地塞米松对未成熟B细胞上分化标志物CD10/NEP表达的影响。该药物以对应于生理范围的浓度应用。在三个表达水平上测量CD10/NEP：mRNA（通过双链PCR）、膜蛋白标志物（流式细胞术分析）和酶活性（选择性显色底物的水解）。地塞米松以浓度和时间依赖性方式下调未成熟B细胞系NALM-6上的CD10/NEP表达。在所有三个水平上均检测到该效应。地塞米松诱导的CD10/NEP下调是通过糖皮质激素受体（GR）介导的，因为它被GR拮抗剂RU 38486完全消除。这在所有三个水平上均发生。地塞米松诱导的CD10/NEP下调机制不太可能包括选择CD10低的细胞，因为在去除地塞米松后该效应部分可逆。然而，地塞米松诱导的CD10/NEP下调确实包括CD10 mRNA转录的减少。转录抑制剂放线菌素D完全消除了地塞米松诱导的CD10/NEP下调。由于正常B淋巴细胞的分化与CD10/NEP的下调有关，所呈现的数据表明，低浓度、生理相关浓度的糖皮质激素（如在急性应激中观察到的）可能在B淋巴细胞的正常发育和成熟中发挥调节作用。
