Immunohistochemical observations of dividing cells in olfactory epithelium using anti-BrdU antibody

Summary To examine the dividing cells in the olfactory epithelium, an experiment using a novel immunohistochemical technique with bromodeoxyuridine (BrdU) was performed. Tissue specimens were obtained from the olfactory epithelium of guinea pigs at days 7 and 21 after olfactory nerve axotomy. BrdU uptake was detected in the epithelial cell layer directly above the basal cell layer rather than in the basal cells per se. The BrdU-immunoreactive cells were found more numerously at 7 days than at 21 days after axotomy. The basal cells showed no immunoreaction to the anti-BrdU antibody on either day. The cells reacting with the anti-BrdU antibody also showed no reaction to the anti-cytokeratin antibody used to identify the basal cells. These findings indicate that the cells showing mitotic activity have characteristics different from those of basal cells, which has been considered previously to be the precursors of regenerating olfactory receptor cells.     

The effect of basic fibroblast growth factor on the regeneration of guinea pig olfactory epithelium

Olfactory receptor cells are widely thought to regenerate after degeneration and also thought to show turnover in normal circumstances in animal olfactory epithelium. The identity of the factor that controls proliferation and differentiation of olfactory receptor cells is a very important problem that has yet to be resolved. In this study, the mitogenic effects of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) on olfactory receptor cells in guinea pig olfactory epithelium was examined. The intraperitoneal injection of 1,000 ng bFGF/day for 14 days increased the cells in proliferation detected by immunostaining with proliferating cell nuclear antigen (PCNA), while neither EGF nor low-dose bFGF had any effect. These results support the idea that an adequate dose of bFGF plays an important role in the neurogenesis in the olfactory epithelium. Further study is needed to clarify the efficacy of bFGF in the damaged olfactory epithelium, but bFGF may provide a therapeutic option for olfactory disturbances caused by complete or partial loss of olfactory receptor cells. Received: 3 October 2001 / Accepted: 10 October 2001     

Upregulation of neural growth-associated protein and neural cell adhesion molecule in mouse olfactory epithelium and axons after unilateral removal of the olfactory bulb

The expression of synaptosomal-associated protein (SNAP-25), neural growth-associated protein (GAP-43) and neural cell adhesion molecule (NCAM) were studied in mouse olfactory cells and axons for 2 weeks following unilateral bulbectomy. The olfactory cells and axons in the control olfactory epithelium were positive for SNAP-25 but levels decreased in the atrophic olfactory epithelium 3 days after bulbectomy. There was no expression of SNAP-25 in the olfactory epithelium on the bulbectomy side 7 days after bulbectomy, indicating that this protein may be a good marker for the degeneration of olfactory cells. The expression of NCAM was still found in the atrophic olfactory epithelium at 7 days after bulbectomy, while the expression of NCAM in the olfactory epithelium of the bulbectomy side was stronger than that on the control side at 14 days after bulbectomy. The expression of GAP-43 in the olfactory axonal bundles of the bulbectomy side at 3 and 4 days after bulbectomy was stronger than that on the control side. These results suggest that upregulation of NCAM may be related to the regeneration of the olfactory cells, with upregulation of GAP-43 probably playing a role in axonal regeneration after bulbectomy. Received: 6 January 1998 / Accepted: 22 April 1998     

The dynamics of precursor cells in the olfactory epithelium of juvenile and adult guinea pigs

The dynamics of precursor cells in the olfactory epithelium of juvenile and adult guinea pigs were examined by immunohistochemical double staining using bromodeoxyuridine (BrdU), the neural cell adhesion molecule (N-CAM) and the protein gene product 9.5 (PGP9.5). Expression of apoptotic cells in the olfactory epithelium with the use of the TdT-mediated dUTP biotin nick end labeling (TUNEL) method was also observed. BrdU was given to healthy guinea pigs at the ages of 2 weeks and 6 months old. Tissue specimens were serially collected 1 h to 28 days after administration. BrdU-labeled cells were seen above the basal cell layer after 1 h and migrated to the middle layer of the olfactory epithelium, after 1 day in juveniles and 5 days in adults with expression of N-CAM. PGP9.5 was observed in BrdU-labeled cells after 5 days in juvenile guinea pigs and 7 days in adult. At 14 days after administration, BrdU-labeled cells in the epithelium appeared to decrease. However, a few of these cells were recognized above the basal cell layer after 28 days. The number and location of TUNEL-positive cells did not significantly differ between the juvenile and adult olfactory epithelium. Therefore, we conclude that the division speed from stem cells in juveniles is faster than that in adults, and apoptosis is unaffected by aging in the normal olfactory epithelium.     

上呼吸道感染后嗅觉障碍患者嗅上皮超微结构观察

目的通过对上呼吸道感染后嗅觉障碍的患者鼻腔大体及嗅上皮超微结构的研究，从形态学上观察嗅觉减退或丧失的超微结构改变。方法选择上呼吸道感染后嗅觉减退或丧失患者10例，用T＆T嗅觉测试法测试患者的嗅觉功能。常规前鼻镜、鼻内镜下对鼻腔大体结构进行观察，鼻内镜下钳取嗅区黏膜行透射电镜超微结构观察。结果上呼吸道感染后嗅觉障碍患者嗅黏膜超微结构有以下变化：①嗅上皮结构层次仍能保持，但细胞间隙增宽；②上皮表面嗅泡明显减少，即使嗅泡存在，其末端的纤毛也明显减少，部分嗅泡呈空泡状改变；③微绒毛细胞和支持细胞表面的微绒毛减少或缺失；④支持细胞的细胞核变形或固缩，嗅细胞的树突水肿变形，细胞器减少。结论上呼吸道感染后嗅觉功能障碍与嗅黏膜上皮超微结构的改变密切相关。患者嗅泡及嗅泡内纤毛缺失，微绒毛细胞及支持细胞的微绒毛减少是引起嗅觉减退的主要原因，支持细胞胞核的变形及嗅细胞树突的形态学改变与嗅觉改变相关。     

神经元核心抗原在小鼠嗅球和嗅上皮发育中的表达

目的：探讨神经元核心抗原（NeuN）在嗅球和嗅上皮发育过程中的表达特性和意义。方法：在小鼠胚胎发育9．5、11．5、14．5、17．5d,出生当天和3个月成年个体的头部切片标本中,以免疫荧光染色方法检测NeuN的表达。结果：刚出生小鼠嗅球内层状结构尚不明显,NeuN表达于嗅球周边区域。在3个月大成年小鼠,嗅球的层状结构已清晰可见,NeuN表达阳性的成熟神经元主要聚集于接近嗅球中心的颗粒细胞层。位于嗅上皮的双极嗅感觉神经元在小鼠胚胎和成年个体中均未见NeuN表达。结论：NeuN通常被认为表达于几乎所有部位的成熟神经元。但在嗅球和嗅上皮中,NeuN只表达于成熟嗅球中的颗粒细胞层。小鼠出生到发育为成熟个体的过程中,NeuN表达阳性的成熟神经细胞由周边逐渐向嗅球中心迁移,可能与气味模式的形成有关。     

大鼠嗅感觉上皮发育及嗅细胞凋亡的研究

目的 探讨神经特异性烯醇酶（NSE）、嗅细胞标记蛋白（OMP）及细胞凋亡在不同胎龄大鼠嗅黏膜中的表达。方法 免疫组化方法检测NSE及OMP在不同孕期大鼠嗅上皮中的表达及其规律。TUNEL方法检测不同孕期大鼠嗅上皮中凋亡细胞并计算细胞凋亡指数（AI）。结果 E13d鼻腔黏膜中即有NSE阳性表达,细胞数量多。E13d嗅上皮中未见OMP阳性表达细胞。在E14d,嗅上皮中出现嗅OMP阳性细胞,数量少,随胎龄增加阳性细胞数量增多,至17d达高峰并逐渐趋于稳定。E13～E15d细胞凋亡数量较稳定,至E16d凋亡细胞数量明显增加,达到高峰,E18～E21d凋亡细胞数量逐渐减少渐趋于稳定。E16dAI与其他d数差异有统计学意义。结论 E14d嗅黏膜中已有发育成熟的嗅细胞,数量少,胚胎发育后期大鼠嗅化学感受器发育已趋于成熟。在嗅上皮发育过程中存在细胞凋亡,E16d嗅细胞凋亡出现一高峰,细胞凋亡在嗅觉发育过程中起重要作用。     

缺血对大鼠嗅球影响的实验研究

目的：观察成年大鼠嗅球缺血性损伤后的病理改变,探讨缺血对嗅觉的影响。方法：选取40只成年SD大鼠（体重250-300g）,分成对照组、实验组（1周组、1月组、2月组）,每组10只。将实验组大鼠双侧颈总动脉结扎造成缺血,分别在1周、1个月、2个月时处死,光镜下观察嗅球病理改变,透射电镜下观察嗅球内细胞超微结构的变化。结果：光镜下可见实验组大鼠嗅球僧帽细胞胞核深染、颗粒细胞数目减少。透射电镜下1周组大鼠嗅球内僧帽细胞线粒体破坏,细胞变性、坏死;1月组僧帽细胞退行性变,神经纤维髓鞘断裂、板层脱落。结论：缺血可损伤神经细胞和神经纤维,可能造成或加重嗅觉障碍。     

慢性鼻窦炎嗅觉障碍患者嗅上皮超微结构观察

目的观察慢性鼻窦炎嗅觉障碍患者嗅上皮的超微结构变化。方法对35例住院行鼻内窥镜手术治疗伴有嗅觉缺失鼻窦炎患者的嗅上皮取活体组织,光镜下将嗅上皮按病变分为正常、萎缩和呼吸上皮化生组,透射电镜分别观察各组超微结构变化。结果①光镜下正常的嗅上皮细胞表面超微结构出现支持细胞微绒毛消失、嗅泡内微管结构消失或空泡化致嗅泡变形、嗅纤毛变形或减少、少量纤毛化生等改变;②萎缩的嗅上皮超微结构改变的特点轻、中度萎缩主要为支持细胞上部的细胞器和膜限制性的电子致密囊泡明显减少或消失、空泡化,基底细胞退行性变;重度萎缩为细胞结构不清,多为双层细胞结构,细胞核染色质呈斑块状凝聚、核空泡化或核固缩;细胞质内均出现内质网扩张,线粒体肿胀、嵴排列紊乱、减少或空泡状改变;③呼吸上皮化生区域,丛状纤毛细胞与支持细胞、嗅泡样结构间隔分布,即嗅上皮细胞呈岛状分布。结论炎症导致嗅上皮细胞由表层及里层各种超微结构异常程度与嗅上皮萎缩程度呈正相关;慢性鼻窦炎嗅觉障碍患者嗅上皮超微结构变化与分型分期无关。     

嗅神经切断对小鼠嗅感觉神经元的影响

目的分析嗅神经切断对小鼠嗅感觉神经元（olfactory receptor neurons，ORN）凋亡情况的影响，并探讨这一造模方法的可靠件。方法取2月龄C57小鼠33只，随机分组后，实验组小鼠行嗅神经切断术，通过辣根过氧化物酶（horseradish peroxidase，HRP）顺行神经示踪验证造模成功与否。以脱氧核苷酸转移酶介导的牛物素dUTP缺口末端标记技术（TdT mediated deoxyuridine triphosphate—biotin nick end labelling，TUNEI。）观察术后8h、2d、3d和5d嗅上皮中ORN的凋亡情况，同时在蛋白和mRNA水平观察成熟ORN的特异性标记蛋白——嗅标记蛋白（olfactory marker protein，OMP）在嗅上皮巾的表达情况。结果嗅神经切断术后嗅球中无HRP标记。TUNEL和OMP阳性反应发生于ORN，嗅神经切断术后TUNEL阳性细胞数显著增多，并于术后第2天达到高峰，与此同时OMPmRNA的表达水平开始显著下降，并住术后第5天降至更低，嗅上皮的厚度也相应变薄。结论本实验所采取的造模方法可以较可靠地切断小鼠的嗅神经，并造成小鼠嗅上皮中ORN的同步凋亡。     

神经特异性烯醇化酶及嗅标记蛋白在不同胎龄胎儿嗅黏膜中的表达

目的　探讨神经特异性烯醇化酶 (neuron specificenolase ,NSE)及嗅标记蛋白 (olfactorymarkerprotein ,OMP)在不同胎龄胎儿嗅黏膜中的表达。方法　以免疫组化方法检测NSE及OMP在1 2、1 6、2 0、2 4、2 8和 34周 6例不同胎龄胎儿嗅黏膜中的表达。结果　NSE免疫阳性反应在孕 1 2～ 34周的胎儿嗅黏膜中均有表达 ,各胎龄胎儿嗅黏膜切片中均可见大量阳性着色的双极嗅神经细胞。孕1 2周时 ,阳性细胞数量很多 ,排列紧密 ,胞体多位于嗅上皮中下部且阳性嗅神经上皮占据胎儿鼻腔上2 /3的黏膜 ,随着孕龄的增大 ,阳性细胞逐渐成多层次排列 ,所占鼻腔黏膜面积却逐渐减小 ,至孕 34周时 ,仅局限于鼻腔上 1 /3黏膜。OMP免疫反应在孕 1 2周胎儿鼻腔上 2 /3黏膜切片中仅发现少量阳性着色的双极神经细胞 ,明显少于同龄胎儿NSE阳性反应细胞。随着胎龄的增加 ,OMP阳性细胞逐渐增多 ,且胞体多位于嗅上皮中上部 ,但其数量仍相对少于同龄NSE阳性细胞。结论　人胚胎 1 2周时嗅黏膜中已有大量的嗅神经细胞 ,其中少数嗅神经细胞已开始发育成熟。随着胎龄的增大 ,嗅上皮面积逐渐缩小 ,但成熟的嗅神经细胞逐渐增多 ,胚胎发育后期的胎儿嗅化学感受器发育已趋于成熟     

大鼠嗅上皮神经干细胞的分离及培养

目的：从新生及成年大鼠嗅上皮分离培养嗅上皮神经干细胞（NSC）,研究其增殖及分化特性。方法：采用含10％胎牛血清的DMEM／F12（1：1）培养液,分离、培养生后第3天和硫酸锌原位创伤后6d的成年大鼠嗅上皮NSC,应用间接免疫荧光染色鉴定培养的NSC及分化的特异性神经细胞类型,四甲基偶氮唑盐法（MTT）测定嗅上皮NSC的生长曲线及生长因子的影响。结果：从生后第3天和成年大鼠嗅上皮分离、培养出巢蛋白免疫反应阳性而细胞角蛋白免疫反应阴性,并能分化为神经元和星形胶质细胞的NSC。生后第3天和成年大鼠嗅上皮NSC生存能力的差异无统计学意义（P〉O．05）,细胞克隆形成率为0．05％～0．10％。碱性成纤维细胞生长因子可以显著促进嗅上皮NSC的增殖。结论：从生后第3天和成年大鼠嗅上皮可培养出具有自我复制和多向分化潜能的NSC。     

A re-evaluation of the classification of olfactory epithelia in patients with olfactory disorders

Summary We have previously demonstrated that human olfactory epithelia can be classified into five grades according to the degree of degeneration present in patients with various kinds of olfactory disorders. In practice, however, the occurrence of additional types of cell changes in other kinds of olfactory disorders and findings with immunohistochemical techniques have led us to re-evaluate our previous classification. In the present study, changes in olfactory epithelia from ten patients with various kinds of olfactory disorders are discussed and a revised classification is proposed. Microvillar and differentiating cells were also evaluated in the epithelium studied. Correspondence to: M. Yamagishi     

Olfactory disturbances caused by the anti-cancer drug tegafur

Olfactory disturbances induced by the anticancer drug tegafur were studied in separate clinical and experimental investigations. Five patients with olfactory dysfunction after tegafur were studied and were found to have normal endoscopic findings of the olfactory cleft mucosa. The average period for drug administration was 22 months. Recovery from the olfactory disturbance was poor and biopsy of the olfactory mucosa revealed severely degenerated epithelium. In experimental studies in a guinea pig animal model, effects of oral tegafur on mitotic cells in the olfactory epithelium were examined using bromodeoxyuridine (BrdU) uptake as index. At the conclusion of 3 weeks' treatment, no pronounced morphological changes were seen, but the number of BrdU-incorporating cells decreased in proportion to the dose of tegafur used. Following long-term administration of tegafur 18 months, mitotic cells reacting to BrdU or proliferating cell nuclear antigen had virtually disappeared, indicating persistent inhibition of mitotic cell activity. Morphological changes present included decreased olfactory cell numbers, loss of cells in areas just above basal cells and degeneration of the mucous layer.     

Olfactory Epithelium Grafts in the Cerebral Cortex: An Immunohistochemical Analysis

Objective To develop an alternative model for studying the regenerative capacity of olfactory neurons. Study Design An immunohistochemical analysis of mouse olfactory epithelium transplanted to the cerebral cortex. Methods Strips of olfactory epithelium removed from donor mice at postnatal day 5 to day 20 were inserted into the parietal cortex of adult mice. Recipient animals were allowed to survive for 25 to 120 days and then perfused with 4% paraformaldehyde 1 hour after bromodeoxyuridine injection. The brains were processed, and frozen sections were obtained. Sections through transplant tissue were analyzed using immunohistochemistry and compared with normal olfactory epithelium. Results Graft survival approached 85% with mature olfactory neurons detected in 35% of the transplants stained for olfactory marker protein. Transplant epithelium resembled normal olfactory epithelium containing mature olfactory neurons and axon bundles. Conclusions Studies of olfactory neuron regeneration have been limited by the inability to produce cultures with long‐term viability. Olfactory epithelial grafts to the cerebral cortex provide an alternative approach to the study of olfactory neuron regeneration.     

P物质在慢性鼻窦炎嗅黏膜中的表达及其意义

目的 :探讨慢性鼻窦炎患者嗅觉功能障碍的发病机制。方法 :采用免疫组织化学方法对慢性鼻窦炎5 5例和对照组 11例的嗅黏膜进行P物质 (SP)检测 ;用苏木精 伊红染色方法观察嗜酸性粒细胞的浸润程度。结果 :鼻窦炎组嗅黏膜嗜酸性粒细胞阳性者 4 9例 (89.1% ) ,对照组 1例 (18.2 % ) ,差异有统计学意义 (P <0 .0 5 ) ;SP在慢性鼻窦炎嗅黏膜的嗅细胞、支持细胞、基底细胞、腺体、血管上皮及部分淋巴细胞、嗜酸性粒细胞中均有阳性表达 ,鼻窦炎组阳性表达 4 5例 (81.8% ) ,对照组 1例 (9.1% ) ,差异有统计学意义 (P <0 .0 1)。结论 :慢性鼻窦炎嗅黏膜的变态反应性改变是引起嗅觉功能障碍的主要因素之一 ,与SP在嗅黏膜中表达增高有关。     

Pathology of the olfactory epithelium: smoking and ethanol exposure

OBJECTIVE: To investigate the effects of tobacco smoke on the olfactory epithelium. Cigarette smoking has been associated with hyposmia; however, the pathophysiology is poorly understood. The sense of smell is mediated by olfactory sensory neurons (OSNs) exposed to the nasal airway, rendering them vulnerable to environmental injury and death. As a consequence, a baseline level of apoptotic OSN death has been demonstrated even in the absence of obvious disease. Dead OSNs are replaced by the mitosis and maturation of progenitors to maintain sufficient numbers of neurons into adult life. Disruption of this balance has been suggested as a common cause for clinical smell loss. This current study will evaluate the effects of tobacco smoke on the olfactory mucosa, with emphasis on changes in the degree of OSN apoptosis. STUDY DESIGN: A rat model was used to assess the olfactory epithelium after exposure to tobacco smoke. METHODS: Rats were exposed to tobacco smoke alone (for 12 weeks), smoke plus dietary ethanol (for the final 5 weeks), or to neither (control). Immunohistochemical analysis of the olfactory epithelium was performed using an antibody to the active form of caspase-3. Positive staining for this form of the caspase-3 enzyme indicates a cell undergoing apoptotic proteolysis. RESULTS: Control rats demonstrated a low baseline level of caspase-3 activity in the olfactory epithelium. In contrast, tobacco smoke exposure triggered a dramatic increase in the degree of OSN apoptosis that affected all stages of the neuronal lineage. CONCLUSIONS: These results support the following hypothesis: smell loss in smokers is triggered by increased OSN death, which eventually overwhelms the regenerative capacity of the epithelium.     

Immunohistopathology of variations of human olfactory mucosa

Summary The characteristics of the human olfactory mucosa were studied immunohistologically. Regular, tonal distribution of the supporting cells, multilayered olfactory receptor cells and basal cells was commonly found in the olfactory mucosa of the human fetus. In contrast, most of the olfactory mucosa in the adult varied to some extent. In the relatively thick, slightly degenerated olfactory mucosa, olfactory marker protein positive receptor cells were arranged irregularly. The most common evidence for variation was the decrease or disappearance of the olfactory receptor cells. Serous-type lactorferrin-containing glandular acini were characteristically found beneath degenerated epithelium. Islands of respiratory epithelium were also seen. The ductules of the Bowman's glands were distended and the openings of these ductules were wide. There was invagination or epithelial cell processes into the glandular lumina. These findings suggest that the epithelial cells of Bowman's glands play an important role in the regeneration of the human olfactory mucosa. Offprint requests to: T. Nakashima     

Biopsy of the olfactory epithelium from the superior nasal septum: is it possible to obtain neurons without damaging olfaction?

IntroductionOlfactory epithelium biopsy has been useful for studying diverse otorhinolaryngological and neurological diseases, including the potential to better understand the pathophysiology behind COVID-19 olfactory manifestations. However, the safety and efficacy of the technique for obtaining human olfactory epithelium are still not fully established.ObjectiveThis study aimed to determine the safety and efficacy of harvesting olfactory epithelium cells, nerve bundles, and olfactory epithelium proper for morphological analysis from the superior nasal septum.MethodsDuring nasal surgery, 22 individuals without olfactory complaints underwent olfactory epithelium biopsies from the superior nasal septum. The efficacy of obtaining olfactory epithelium, verification of intact olfactory epithelium and the presence of nerve bundles in biopsies were assessed using immunofluorescence. Safety for the olfactory function was tested psychophysically using both unilateral and bilateral tests before and 1 month after the operative procedure.ResultsOlfactory epithelium was found in 59.1% of the subjects. Of the samples, 50% were of the quality necessary for morphological characterization and 90.9% had nerve bundles. There was no difference in the psychophysical scores obtained in the bilateral olfactory test (University of Pennsylvania Smell Identification Test [UPSIT®]) between means before biopsy: 32.3 vs. postoperative: 32.5, p = 0.81. Also, no significant decrease occurred in unilateral testing (mean unilateral test scores 6 vs. 6.2, p = 0.46). None out of the 56 different odorant identification significantly diminished (p > 0.05).ConclusionThe technique depicted for olfactory epithelium biopsy is highly effective in obtaining neuronal olfactory tissue, but it has moderate efficacy in achieving samples useful for morphological analysis. Olfactory sensitivity remained intact.     

Lipopolysaccharide-induced apoptosis of olfactory receptor neurons in rats

CONCLUSION: Daily intranasal perfusion of lipopolysaccharide (LPS) for 14 days in rats induced apoptosis of olfactory receptor neurons (ORNs) over >3 but <7 days. OBJECTIVES: Smoking is one of the factors causing olfactory dysfunction. LPS is a major glycolipid component of the gram-negative bacterial cell wall and an active component of cigarette smoke. We studied whether LPS is one of the causes of tobacco-induced olfactory dysfunction by examining apoptosis in the olfactory epithelium after local exposure to LPS. MATERIALS AND METHODS: Rats received intranasal instillation of LPS or saline. Histochemical changes in the olfactory epithelium were examined using antibodies against single-stranded DNA, Bcl-2, Bax, and Caspase-3. We used different concentrations of LPS to examine the dose dependency and observed changes in the olfactory epithelium for a week after exposure cessation to see the duration of the effect of smoking. RESULTS: We found that numbers of cells positive for ssDNA, Bcl-2, Bax, and Caspase-3 were increased on the exposed side. The number of ssDNA-positive cells reached a maximum on the first day and decreased to normal levels on the seventh day after cessation of exposure.