Ueha Rumi, Ueha Satoshi, Kondo Kenji, Sakamoto Takashi, Kikuta Shu, Kanaya Kaori, Nishijima Hironobu, Matsushima Kouji, Yamasoba Tatsuya
Department of Otolaryngology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Am J Pathol. 2016 Mar;186(3):579-86. doi: 10.1016/j.ajpath.2015.11.009. Epub 2016 Jan 22.
Exposure to cigarette smoke is a major cause of olfactory dysfunction. However, the underlying mechanisms by which cigarette smoke interferes with the highly regenerative olfactory nerve system remain unclear. To investigate whether cigarette smoke induces olfactory dysfunction by disrupting cell proliferation and cell survival in the olfactory epithelium (OE), we developed a mouse model of smoking that involved intranasal administration of a cigarette smoke solution (CSS). Immunohistological analyses and behavioral testing showed that CSS administration during a period of 24 days reduced the number of olfactory marker protein-positive mature olfactory receptor neurons (ORNs) in the OE and induced olfactory dysfunction. These changes coincided with a reduction in the number of SOX2(+) ORN progenitors and Ki-67(+) proliferating cells in the basal layer of the OE, an increase in the number of caspase-3(+) apoptotic cells, and an increase in the expression of mRNA for the inflammatory cytokines IL-1β and IL-6. Notably, the proliferating ORN progenitor population recovered after cessation of treatment with CSS, resulting in the subsequent restoration of mature ORN numbers and olfaction. These results suggest that SOX2(+) ORN progenitors are targets of CSS-induced impairment of the OE, and that by damaging the ORN progenitor population and increasing ORN death, CSS exposure eventually overwhelms the regenerative capacity of the epithelium, resulting in reduced numbers of mature ORNs and olfactory dysfunction.
接触香烟烟雾是嗅觉功能障碍的主要原因。然而,香烟烟雾干扰高度再生的嗅觉神经系统的潜在机制仍不清楚。为了研究香烟烟雾是否通过破坏嗅觉上皮(OE)中的细胞增殖和细胞存活来诱导嗅觉功能障碍,我们建立了一种吸烟小鼠模型,该模型涉及经鼻给予香烟烟雾溶液(CSS)。免疫组织学分析和行为测试表明,在24天内给予CSS会减少OE中嗅觉标记蛋白阳性的成熟嗅觉受体神经元(ORN)数量,并诱导嗅觉功能障碍。这些变化与OE基底层中SOX2(+) ORN祖细胞和Ki-67(+)增殖细胞数量的减少、caspase-3(+)凋亡细胞数量的增加以及炎性细胞因子IL-1β和IL-6的mRNA表达增加相一致。值得注意的是,在用CSS治疗停止后,增殖的ORN祖细胞群体得以恢复,随后成熟ORN数量和嗅觉也得以恢复。这些结果表明,SOX2(+) ORN祖细胞是CSS诱导的OE损伤的靶点,并且通过损害ORN祖细胞群体和增加ORN死亡,接触CSS最终会超过上皮的再生能力,导致成熟ORN数量减少和嗅觉功能障碍。