Constant inhibition of local BMP signaling contributes to recovery of mucociliary epithelium from Tracheobronchopathia Osteochondroplastica (TO)-associated pathophysiology via basal cell restoration

Tracheobronchial basal cells have been found to undergo persistent functional changes, via acting as a local repository for BMP signaling elements, thereby play a driven role in TO pathogenesis. Although it would be unlikely to fundamentally correct cell fate alteration, because of epigenetic changes occurred, partial restoration of epithelial physiology may be achieved by braking self-amplifying BMP signaling loop. To investigate the effect of BMP inhibition on TO-derived basal cells, ALI structures derived from routine differentiation without Noggin treatment and modified differentiation with constant BMP inhibition were subjected to RNA-sequencing. While a differentiation pattern of 3538 genes up-regulated and 2109 genes down-regulated (>2-fold or <-2-fold, p<0.05) upon routine differentiation of a typical TO-derived pedigree, differentiation in the presence of BMP inhibition resulted in an up-regulation of 4101 genes and down-regulation of 2337 genes (equivalent cutoff as above). Among those 1554 genes with significantly increased expression on ALI under BMP inhibition, a major enrichment shown up in categories related to cilium assembly and function, and an up-turned Smoothened signaling were detected. In contrast, 482 genes with decreased expression under BMP inhibition were mainly fallen into categories related to biomineral tissue development. These data suggest that constant repression of local BMP signaling has a favorable effect, to some extent, on functional rescue of pathological basal cells. Overall design: Samples at stem cell state, differentiated without BMP inhibitor treatment and differentiated along BMP inhibition were analyzed by RNA-Seq, in singleton.

研究表明，气管支气管基底细胞可作为骨形态发生蛋白（BMP, Bone Morphogenetic Protein）信号分子的局部储存库，发生持续性功能改变，进而在TO发病过程中发挥驱动作用。尽管由于表观遗传改变的存在，难以从根本上纠正细胞命运的改变，但通过抑制自我放大的BMP信号环路，可部分恢复上皮生理功能。为探究BMP抑制对TO来源基底细胞的影响，本研究对两类气液界面（ALI, Air-Liquid Interface）培养结构开展RNA测序（RNA-seq）：一类为未经Noggin蛋白处理的常规分化组，另一类为持续施加BMP抑制的改良分化组。在典型TO来源细胞谱系的常规分化过程中，共出现3538个基因上调、2109个基因下调（差异倍数≥2倍或≤-2倍，p<0.05）；而在BMP抑制条件下的分化过程中，上调基因数为4101个，下调基因数为2337个（差异筛选阈值与前述一致）。在BMP抑制条件下ALI培养中表达显著上调的1554个基因中，主要富集于纤毛组装与功能相关的功能条目，同时检测到Smoothened信号通路的激活上调。与之相反，BMP抑制条件下表达下调的482个基因，主要富集于生物矿化组织发育相关的功能条目。上述数据表明，持续抑制局部BMP信号通路，在一定程度上可实现病变基底细胞的功能挽救。实验整体设计：对干细胞状态样本、未经BMP抑制剂处理的分化样本以及经BMP抑制处理的分化样本进行单样本RNA测序（RNA-seq）分析。