Microbiota-derived lipopolysaccharide retards chondrocyte hypertrophy in the growth plate through elevating Sox9 expression
Microbiota-derived lipopolysaccharide retards chondrocyte hypertrophy in the growth plate through elevating Sox9 expression
复制标题
微生物群衍生的脂多糖通过提高 Sox9 表达来延缓生长板中的软骨细胞肥大
DOI：
10.1002/jcp.27025
复制
发表时间：
2019-03-01
影响因子：
5.6
通讯作者：
Yang, Xuesong
中科院分区：
文献类型：
--
作者：
Cheng, Xin;Li, Pei-Zhi;Yang, Xuesong
越来越多的数据表明，来自微生物群或感染的细菌脂多糖（LPS）的细胞毒性与临床上观察到的许多疾病有关。然而，胚胎成骨是否受到妊娠期LPS暴露的影响仍不清楚。采用早期鸡胚模型，通过阿辛蓝染色和茜素红染色，我们可以证明LPS暴露抑制了8天鸡胚的软骨形成和17天鸡胚的成骨形成。进一步分析生长板显示，LPS暴露后，增殖区（PZ）的长度增加，而肥大区（HZ）的长度减少。然而，在生长板中的细胞增殖没有显著变化。免疫荧光染色、western blot分析和定量聚合酶链反应显示，Sox 9和Col2a1在mRNA水平上高度表达，其蛋白产物也很丰富。LPS暴露导致8天后肢中Runx2和Col10a1表达下调，17天趾骨中Runx2、Col10a1和Vegfa表达抑制。通过小干扰RNA（siRNA）转染ATDC 5细胞，敲低Sox 9基因，可导致Col2a1、Runx2和Col10a1的表达降低，提示Sox 9在LPS诱导的生长板软骨细胞从增殖期向肥大期转变的延迟过程中起重要作用。在LPS的存在下，抗氧化防御调节核因子（红细胞衍生2）样2（Nrf2）的高度表达，超氧化物歧化酶1（SOD 1），SOD 2和谷氧还蛋白的活性上升，在17天的趾骨和ADTC 5细胞。同时，观察到细胞内ROS的增加。当ATDC 5细胞中Nrf2表达被敲低时，Sox 9、Col2a1、Runx 2、Col10a1和Vegfa的表达也随之下降。综上所述，我们目前的数据表明，妊娠期间的LPS暴露可以限制生长板中软骨细胞从增殖到肥大的转化，其中LPS诱导的Sox 9通过过量的ROS产生和Nrf2升高来触发下游基因的级联反应。
Accumulating data show that the cytotoxicity of bacterial lipopolysaccharides (LPS) from microbiota or infection is associated with many disorders observed in the clinics. However, it is still obscure whether or not embryonic osteogenesis is affected by the LPS exposure during gestation. Using the early chicken embryo model, we could demonstrate that LPS exposure inhibits chondrogenesis of the 8-day chicken embryos by Alcian Blue-staining and osteogenesis of 17-day by Alcian Blue and Alizarin Red staining. Further analysis of the growth plates showed that the length of the proliferating zone (PZ) increases whereas that of the hypertrophic zone (HZ) decreased following LPS exposure. However there is no significant change on cell proliferation in the growth plates. Immunofluorescent staining, western blot analysis, and quantitive polymerase chain reaction revealed that Sox9 and Col2a1 are highly expressed at the messenger RNA level and their protein products are also abundant. LPS exposure causes a downregulation of Runx2 and Col10a1 expression in 8-day hindlimbs, and a suppression of Runx2, Col10a1, and Vegfa expression in 17-day phalanges. Knocking down Sox9 in ATDC5 cells by small interfering RNA transfection lead to the expression reduction of Col2a1, Runx2, and Col10a1, implying the vital role of Sox9 in the process of LPS-induced delay in the transition from proliferating chondrocytes to hypertrophic chondrocytes in the growth plate. In the presence of LPS, the antioxidant defense regulator nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is highly expressed, and the activities of superoxide dismutase 1 (SOD1), SOD2, and glutaredoxin rise in 17-day phalanges and ADTC5 cells. Simultaneously, an increase of intracellular ROS is observed. When Nrf2 expression was knocked down in ATDC5 cells, the expressions of Sox9, Col2a1, Runx2, Col10a1, and Vegfa were also going down as well. Taken together, our current data suggest that LPS exposure during gestation could restrict the chondrocytes conversion from proliferating to hypertrophic in the growth plate, in which LPS-induced Sox9 plays a crucial role to trigger the cascade of downstream genes by excessive ROS production and Nrf2 elevation.