Department of Pediatrics, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Okayama, Japan.
Clin Exp Allergy. 2009 Dec;39(12):1857-65. doi: 10.1111/j.1365-2222.2009.03365.x.
Theophylline has an anti-inflammatory action that may account for its clinical effectiveness in the reduction of inflammatory cells in the airways. Dendritic cells (DCs) are professional antigen-presenting cells, capable of priming naïve T cells, and play key roles in the activation of immune responses in asthma.
The purpose of this study was to investigate the effects of theophylline on human monocyte differentiation into DCs and whether this involved antagonism of adenosine receptors.
Peripheral human blood monocytes were cultured in the presence of granulocyte/macrophage-colony stimulating factor and IL-4 to induce DC differentiation. The cells were incubated with theophylline, KF17837 (a selective A2a receptor antagonist) and enprofylline (A2b receptor antagonist) and co-incubated with selective adenosine A1 and A2a receptor agonists, a phosphodiesterase inhibitor (rolipram) and adenosine deaminase (ADA) to determine their effects on DC differentiation. In addition, depletion of adenosine receptors by small interfering RNA (siRNA) was also examined.
Monocytes differentiated into myeloid DCs in the culture system. The number of DCs was remarkably reduced by 60-70% when theophylline was administered at a therapeutic concentration. This effect was concentration-dependently exacerbated, was partly mediated by cellular apoptosis and was effectively reversed by the addition of the A1 agonists [2-chloro-N(6)-cyclopentyladenosin, N(6)-cyclohexyladenosine, and N-ethylcarboxamidoadenosine (NECA)] or the A2a agonist (CGS-21680, NECA). The depletion of the adenosine A1 receptor by siRNA and addition of ADA remarkably reduced DC differentiation. Meanwhile, both enprofylline and rolipram had little effect.
Our findings suggest that the adenosine A1 (and possibly coordinated with A2a) receptors contribute to DC differentiation and survival. These findings provide further evidence that theophylline has an anti-inflammatory action in bronchial asthma.
茶碱具有抗炎作用，这可能解释了其在减少气道炎症细胞方面的临床疗效。树突状细胞（DCs）是专业的抗原呈递细胞，能够激活初始 T 细胞，并在哮喘的免疫反应激活中发挥关键作用。
本研究旨在探讨茶碱对人单核细胞向 DC 分化的影响，以及这种作用是否涉及拮抗腺嘌呤受体。
在粒细胞/巨噬细胞集落刺激因子和 IL-4 的存在下培养外周血人单核细胞，以诱导 DC 分化。将细胞与茶碱、KF17837（一种选择性 A2a 受体拮抗剂）和恩普啡林（A2b 受体拮抗剂）孵育，并与选择性腺嘌呤 A1 和 A2a 受体激动剂、磷酸二酯酶抑制剂（罗利普兰）和腺苷脱氨酶（ADA）共孵育，以确定它们对 DC 分化的影响。此外，还通过小干扰 RNA（siRNA）耗竭腺嘌呤受体进行了研究。
单核细胞在培养系统中分化为髓样 DC。当茶碱以治疗浓度给药时，DC 的数量显著减少了 60-70%。这种作用呈浓度依赖性加剧，部分通过细胞凋亡介导，并可通过添加 A1 激动剂[2-氯-N（6）-环戊基腺苷、N（6）-环己基腺苷和 N-乙基羧酰胺腺苷（NECA）]或 A2a 激动剂（CGS-21680，NECA）有效逆转。siRNA 耗竭腺嘌呤 A1 受体和添加 ADA 可显著减少 DC 分化。同时，恩普啡林和罗利普兰的作用很小。
我们的发现表明，腺嘌呤 A1（可能与 A2a 协调）受体有助于 DC 分化和存活。这些发现进一步证明茶碱在支气管哮喘中具有抗炎作用。
