Circulating complexes of the vitamin D binding protein with G-actin induce lung inflammation by targeting endothelial cells

This study investigated the actin scavenger function of the vitamin D binding protein (DBP) in vivo using DBP null (−/−) mice. Intravenous injection of G-actin into wild-type (DBP+/+) and DBP−/− mice showed that contrary to expectations, DBP+/+ mice developed more severe acute lung inflammation. Inflammation was restricted to the lung and pathological changes were clearly evident at 1.5 and 4 h post-injection but were largely resolved by 24 h. Histology of DBP+/+ lungs revealed noticeably more vascular leakage, hemorrhage and thickening of the alveolar wall. Flow cytometry analysis of whole lung homogenates showed significantly increased neutrophil infiltration into DBP+/+ mouse lungs at 1.5 and 4 h. Increased amounts of protein and leukocytes were also noted in bronchoalveolar lavage fluid from DBP+/+ mice 4 h after actin injection. In vitro, purified DBP-actin complexes did not activate complement or neutrophils but induced injury and death of cultured human lung microvascular endothelial cells (HLMVEC) and human umbilical vein endothelial cells (HUVEC). Cells treated with DBP-actin showed a significant reduction in viability at 4 h, this effect was reversible if cells were cultured in fresh media for another 24 h. However, a 24-h treatment with DBP-actin complexes showed a significant increase in cell death (95% for HLMVEC, 45% for HUVEC). The mechanism of endothelial cell death was via both caspase-3 dependent (HUVEC) and independent (HLMVEC) pathways. These results demonstrate that elevated levels and/or prolonged exposure to DBP-actin complexes may induce endothelial cell injury and death, particularly in the lung microvasculature.     

miR-143-3p靶向IL-6R/STAT3通路抑制IL-6诱导的人肺微血管内皮细胞血管生成

目的探究miR-143-3p在IL-6诱导的人肺微血管内皮细胞(HLMVEC)血管生成中的作用和机制。方法首先使用100 ng/ml重组IL-6蛋白处理HLMVEC细胞,管腔形成实验分析IL-6对细胞管腔形成数目的影响,Real-time PCR检测IL-6对miR-143-3p和VEGF mRNA表达的影响。Western blot检测VEGF蛋白水平的变化。然后使用miR-143-3p mimics过表达miR-143-3p,按照上述方法检测miR-143-3p对IL-6诱导的管腔形成数目、VEGF mRNA和蛋白表达的影响。此外,使用双荧光素酶报告基因检测法分析miR-143-3p和IL-6R的关系,Real-time PCR检测miR-143-3p过表达对IL-6R mRNA表达的影响,Western blot检测IL-6R、STAT3和磷酸化STAT3(p-STAT3)蛋白水平的变化。结果 IL-6能够增加管腔形成数目和VEGF的表达,降低miR-143-3p的表达。过表达miR-143-3p能够抑制IL-6诱导的管腔形成、VEGF、IL-6R和p-STAT3的表达水平,但是不影响STAT3的表达。此外还发现IL-6R是miR-143-3p的一个靶基因。结论 miR-143-3p能够抑制IL-6诱导的内皮细胞血管生成,这可能是通过抑制IL-6R/STAT3通路发挥作用的。