Abstract：
Prolonged tissue ischemia and inflammation lead to organ deterioration and are often accompanied by microvasculature rarefaction, fibrosis, and elevated systemic Activin A (ActA), the level of which frequently correlates with disease severity. Mesenchymal stromal cells are prevalent in the perivascular niche and are likely involved in tissue homeostasis and pathology. This study investigated the effects of inflammatory cells on modulation of phenotype of adipose mesenchymal stromal cells (ASC) and the role of ActA in this process. Peripheral blood mononuclear cells were activated with lipopolysaccharide (activated peripheral blood mononuclear cells [aPBMC]) and presented to ASC. Expression of smooth muscle/myofibroblast markers, ActA, transforming growth factors beta 1-3 (TGFβ1-3), and connective tissue growth factor (CTGF) was assessed in ASC. Silencing approaches were used to dissect the signaling cascade of aPBMC-induced acquisition of myofibroblast phenotype by ASC. ASC cocultured with aPBMC or exposed to the secretome of aPBMC upregulated smooth muscle cell markers alpha smooth muscle actin (αSMA), SM22α, and Calponin I; increased contractility; and initiated expression of ActA. Interleukin (IL)-1β was sufficient to replicate this response, whereas blocking IL-1β eliminated aPBMC effects. ASC-derived ActA stimulated CTGF and αSMA expression in ASC; the latter independent of CTGF. Induction of αSMA in ASC by IL-1β or ActA-enriched media relied on extracellular enzymatic activity. ActA upregulated mRNA levels of several extracellular matrix proteins in ASC, albeit to a lesser degree than TGFβ1, and marginally increased cell contractility. In conclusion, the study suggests that aPBMC induce myofibroblast phenotype with weak fibrotic activity in perivascular progenitors, such as ASC, through the IL-1β-ActA signaling axis, which also promotes CTGF secretion, and these effects require ActA extracellular enzymatic processing.
摘要：
长时间的组织缺血和炎症导致器官恶化，通常伴有微血管稀疏，纤维化，和全身性激活素A（ActA）升高，其水平通常与疾病严重程度相关。间充质基质细胞普遍存在于血管周围小生境中，可能参与组织稳态和病理学。本研究探讨了炎症细胞对脂肪基质细胞（ASC）表型调节的影响以及ActA在此过程中的作用。外周血单核细胞用LPS(aPBMC)活化并呈递给ASC。平滑肌/肌成纤维细胞标志物和ActA的表达，在ASC中评估TGFβ1-3和CTGF。沉默方法用于解剖aPBMC诱导的ASC获得肌成纤维细胞表型的信号级联。ASC与aPBMC共培养或暴露于aPBMC的分泌组上调平滑肌细胞标志物αSMA，SM22α,还有CalponinI,收缩力增加，并启动了ActA的表达。IL-1β足以复制这种反应，而阻断IL-1β消除了aPBMC的作用。ASC衍生的ActA刺激ASC中的CTGF和αSMA表达;后者独立于CTGF。IL-1β或ActA富集培养基在ASC中诱导αSMA依赖于细胞外酶活性。ActA上调ASC中几种细胞外基质蛋白的mRNA水平，尽管程度低于TGFβ1，但细胞收缩力略有增加。总之,这项研究表明，aPBMC诱导肌成纤维细胞表型，在血管周围祖细胞中具有弱纤维化活性，像ASC一样，通过IL-1β-ActA信号轴，这也促进CTGF分泌，这些作用需要ActA细胞外酶处理。
