Endothelial MMP14 is required for endothelial dependant growth support of human airway basal cells

Human airway basal cells (BC) are the stem/progenitor population of the airway epithelium, and play a central role in anchoring the epithelium to the basement membrane. The anatomic position of BC allows for potential paracrine signaling between BC and the underlying non-epithelial stromal cells. In support of this, we previously demonstrated endothelial cells (EC) support growth of BC during co-culture via vascular endothelial growth factor A (VEGFA)-mediated signaling. Building on these findings, RNA sequencing analysis demonstrated that BC express multiple fibroblast growth factor (FGF) ligands (FGF2, 5, 11 and 13) with only FGF2 and FGF5 capable of functioning in a paracrine manner to mediate FGFR1 signaling. Antibody mediated blocking of FGFR1 during BC-EC co-culture significantly reduced EC dependent BC growth. Stimulation of EC via BC-derived growth factors resulted in EC expression of matrix metallopeptidase 14 (MMP14) and shRNA mediated knockdown of EC MMP14 significantly reduced EC dependent growth of BC. Overall, these data characterize a novel growth factor mediated reciprocal “cross-talk” between human airway BC and EC that regulates proliferation of BC. Overall design: This study characterizes a novel growth factor mediated reciprocal “cross-talk” between human airway BC and EC that may play a significant role in maintaining normal airway structure.

人类气道基底细胞（BC）是气道上皮的干/祖细胞群，在将上皮锚定至基底膜的过程中发挥核心作用。BC的解剖位置使其具备与下方非上皮基质细胞进行旁分泌信号交流的潜在可能。基于此前提，我们既往的研究证实，在内皮细胞（EC）与BC的共培养体系中，内皮细胞可通过血管内皮生长因子A（VEGFA）介导的信号通路促进BC增殖。基于上述发现，RNA测序分析显示，BC可表达多种成纤维细胞生长因子（FGF）配体（FGF2、5、11及13），其中仅FGF2与FGF5能够以旁分泌方式介导FGFR1信号通路的激活。在BC-EC共培养体系中，通过抗体介导阻断FGFR1可显著降低内皮细胞依赖的BC增殖能力。由BC分泌的生长因子刺激内皮细胞后，可诱导内皮细胞表达基质金属蛋白酶14（MMP14）；而通过短发夹RNA（shRNA）介导敲低内皮细胞的MMP14表达，可显著削弱内皮细胞依赖的BC增殖能力。综上，本研究的数据揭示了一种全新的、由生长因子介导的人类气道BC与EC之间的相互"串扰"机制，该机制可调控BC的增殖。实验整体设计：本研究表征了一种由生长因子介导的人类气道BC与EC之间的相互"串扰"，其可能在维持正常气道结构中发挥重要作用。