Department of Respiratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China.
Chin Med J (Engl). 2012 Jun;125(11):1980-5.
Cigarette smoke-induced emphysema is associated with overexpression of the chemokine receptor CXCR3 and its ligands. Previously, we have demonstrated that pentoxifylline (PTX) alleviated cigarette smoke-induced emphysema. The aim of this study was to determine if the overexpression of CXCR3 and its ligand interferon-inducible protein-10 (IP-10) that was elicited by smoke exposure were attenuated by PTX.
(1) The study in vitro: a given number of RAW264.7 macrophages with decreasing concentrations of PTX in the culture medium were challenged with cigarette smoke extract (CSE); (2) The study in vivo: male BALB/c mice were randomized into four groups, i.e., sham-smoke, smoke only, smoke with 2 mg/kg PTX, and smoke with 10 mg/kg PTX. The smoke exposure time was 90 minutes once a day, 6 days a week for 16 weeks. PTX was given intraperitoneally before each episode of smoke exposure. Interferon (IFN)-γ and IP-10 in broncho-alveolar lavage fluid (BALF) and in culture medium were measured by enzyme-linked immunosorbent assay (ELISA). IP-10 mRNA in lung tissue was assessed by RT-PCR. CXCR3 positive cells in lung sections were visualized by immunochemistry staining.
Up-regulation of IFN-γ and IP-10 in the culture medium of macrophages elicited by CSE was inhibited by PTX in a dose-dependent manner. Chronic cigarette smoke exposure led to overexpression of IFN-γ and IP-10 in BALF, upregulation of IP-10 mRNA and increased infiltration of CXCR3(+) cells into lung parenchyma. Administration of PTX decreased the level of IFN-γ from (6.26 ± 1.38) ng/ml to (4.43 ± 0.66) ng/ml by low dose PTX or to (1.74 ± 0.28) ng/ml by high dose PTX. IP-10 was reduced from (10.35 ± 1.49) ng/ml to (8.19 ± 0.79) ng/ml by low dose PTX or to (7.51 ± 0.60) ng/ml by high dose PTX. The expression of IP-10 mRNA was also down-regulated (P < 0.05). But only with a high dose of PTX was the ratio of CXCR3(+) cells decreased; 15.2 ± 7.3 vs. 10.4 ± 1.8 (P < 0.05).
PTX attenuates cigarette smoke-induced overexpression of chemokine receptor CXCR3 and its ligand IP-10, which is relevant to its inhibitory effect on pulmonary emphysema.
香烟烟雾引起的肺气肿与趋化因子受体 CXCR3 及其配体的过度表达有关。此前，我们已经证明，己酮可可碱（PTX）可减轻香烟烟雾引起的肺气肿。本研究的目的是确定香烟烟雾暴露引起的 CXCR3 及其配体干扰素诱导蛋白-10（IP-10）的过度表达是否被 PTX 减弱。
（1）体外研究：在培养基中含有不同浓度 PTX 的一定数量的 RAW264.7 巨噬细胞受到香烟烟雾提取物（CSE）的挑战；（2）体内研究：雄性 BALB/c 小鼠随机分为四组，即假吸烟组、仅吸烟组、吸烟+2mg/kg PTX 组和吸烟+10mg/kg PTX 组。每天吸烟一次，每次 90 分钟，每周 6 天，共 16 周。在每次吸烟前，通过腹腔内注射给予 PTX。通过酶联免疫吸附试验（ELISA）测量支气管肺泡灌洗液（BALF）和培养基中的干扰素（IFN）-γ和 IP-10。通过 RT-PCR 评估肺组织中 IP-10mRNA 的表达。通过免疫组织化学染色观察肺组织中 CXCR3 阳性细胞。
CSE 诱导的巨噬细胞中 IFN-γ和 IP-10 在培养基中的上调被 PTX 以剂量依赖性方式抑制。慢性香烟烟雾暴露导致 BALF 中 IFN-γ和 IP-10 的过度表达，IP-10mRNA 的上调和 CXCR3（+）细胞浸润到肺实质。低剂量 PTX 或高剂量 PTX 可分别将 IFN-γ的水平从（6.26±1.38）ng/ml 降低至（4.43±0.66）ng/ml 或（1.74±0.28）ng/ml。IP-10 从（10.35±1.49）ng/ml 降低至（8.19±0.79）ng/ml 或（7.51±0.60）ng/ml。IP-10mRNA 的表达也下调（P<0.05）。但只有高剂量的 PTX 才能降低 CXCR3（+）细胞的比例；15.2±7.3 比 10.4±1.8（P<0.05）。
PTX 减轻香烟烟雾引起的趋化因子受体 CXCR3 及其配体 IP-10 的过度表达，这与其对肺气肿的抑制作用有关。
