内耳免疫反应中细胞凋亡的研究

目的探讨内耳免疫反应过程是否引起细胞凋亡以及Fas和FasL、Bcl-2和Bax的表达情况。方法选用雌性白色豚鼠16只，随机分为实验组和对照组各8只，以钥孔蛾血蓝蛋白全身免疫后，实验组以相同抗原进行内耳免疫，对照组内耳注射等量的磷酸盐缓冲生理盐水，在内耳免疫7d后处死动物，取内耳免疫侧耳蜗做石蜡切片。通过电镜和脱氧核糖核苷酸末端转移酶介导的缺口末端标记技术(terminal-deoxynucleotidyl transferase mediated nick end labeling，TUNEL)检测内耳凋亡细胞，免疫组化检测内耳Fas和FasL以及Bcl-2和Bax的表达。结果透射电镜观察发现实验组术后7d内耳外毛细胞、血管纹细胞及螺旋神经节细胞都出现了凋亡细胞的特征性改变，而对照组未发现具有上述特征的细胞。实验组内耳Corti器毛细胞，血管纹的缘细胞和螺旋神经节细胞存在TUNEL染色阳性细胞，TUNEL染色阳性细胞具有凋亡细胞的典型形态学特征，对照组内耳的任何结构中都没发现TUNEL染色阳性细胞。免疫组化染色实验组Corti器、螺旋神经节细胞、血管纹和螺旋韧带Fas和FasL蛋白表达阳性，而对照组只有螺旋神经节细胞和血管纹有较弱的Fas蛋白表达，FasL蛋白表达阴性。实验组Corti器、螺旋神经节细胞、侧壁Bcl-2蛋白表达阴性，对照组的Corti器、侧壁和螺旋神经节细胞Bcl-2蛋白表达阳性。实验组Corti器、侧壁和螺旋神经节细胞Bax蛋白表达阳性，对照组只有螺旋神经节细胞Bax蛋白表达弱阳性，Corti器、侧壁表达阴性。结论内耳免疫反应可诱导细胞凋亡发生，Fas-FasL是此过程的信号转导途径之一，Bcl-2和Bax蛋白在其中起了重要调节作用。     

内耳免疫反应中细胞凋亡的研究

目的　探讨内耳免疫反应过程是否引起细胞凋亡以及Fas和FasL、Bcl 2和Bax的表达情况。方法　选用雌性白色豚鼠 16只 ,随机分为实验组和对照组各 8只 ,以钥孔血蓝蛋白全身免疫后 ,实验组以相同抗原进行内耳免疫 ,对照组内耳注射等量的磷酸盐缓冲生理盐水 ,在内耳免疫 7d后处死动物 ,取内耳免疫侧耳蜗做石蜡切片。通过电镜和脱氧核糖核苷酸末端转移酶介导的缺口末端标记技术 (terminal deoxynucleotidyltransferasemediatednickendlabeling ,TUNEL)检测内耳凋亡细胞 ,免疫组化检测内耳Fas和FasL以及Bcl 2和Bax的表达。结果　透射电镜观察发现实验组术后7d内耳外毛细胞、血管纹细胞及螺旋神经节细胞都出现了凋亡细胞的特征性改变 ,而对照组未发现具有上述特征的细胞。实验组内耳Corti器毛细胞 ,血管纹的缘细胞和螺旋神经节细胞存在TUNEL染色阳性细胞 ,TUNEL染色阳性细胞具有凋亡细胞的典型形态学特征 ,对照组内耳的任何结构中都没发现TUNEL染色阳性细胞。免疫组化染色实验组Corti器、螺旋神经节细胞、血管纹和螺旋韧带Fas和FasL蛋白表达阳性 ,而对照组只有螺旋神经节细胞和血管纹有较弱的Fas蛋白表达 ,FasL蛋白表达阴性。实验组Corti器、螺旋神经节细胞、侧壁Bcl 2蛋白表达阴性 ,对照组的Corti器、侧壁和     

内耳免疫反应中的细胞凋亡活性及其与FasL表达的相关性

目的 观察内耳免疫反应过程中是否存在细胞凋亡以及细胞凋亡活性与FasL表达相关性。方法16只雌性白色豚鼠。随机分为实验组与对照组，每组各8只。所有动物均先以钥孔虫戚血蓝蛋白全身免疫。然后，实验组再以相同抗原进行单侧内耳局部免疫，对照组则于单侧内耳注射等量磷酸盐缓冲生理盐水。3天后处死动物，取内耳免疫侧（或对照注射侧）耳蜗制备石蜡切片，脱氧核糖核苷酸末端转移酶介导的缺口末端标记技术检测内耳细胞凋亡活性，免疫组化法检测内耳FasL表达水平。结果实验组动物内耳Cord器毛细胞、血管纹的缘细胞和螺旋神经节细胞中存在阳性着色的凋亡细胞，对照组豚鼠内耳则否。实验组动物内耳Corti、蜗管侧壁、螺旋神经节细胞FasL表达阳性。对照组则为阴性。结论 内耳免疫反应可诱导局部细胞凋亡活性增高，FasL在此过程中可能发挥重要作用。     

内耳免疫反应中细胞凋亡及Bcl-2与Bax的表达

目的 研究内耳免疫反应时细胞凋亡以及Bcl 2和Bax的表达情况,探讨自身免疫性内耳病发病机制。方法 选用健康SD大鼠60只,随机分成实验组30只（皮下注射Ⅱ型胶原与弗式佐剂）,佐剂组15只（皮下注射弗式佐剂）,对照组15只（予等量生理盐水）,免疫后进行畸变产物耳声发射（DPOAE）检测,扫描电镜形态学观察,DNA末端转移酶介导的缺口末端标记法（TUNEL）检测细胞凋亡及免疫组化检测Bcl-2和Bax的表达。结果 实验组DPOAE幅值下降（P<0.05）,部分毛细胞纤毛排列紊乱、簇状缺失, Corti器、血管纹和螺旋神经节可见TUNEL阳性染色, 且Bax/ Bcl-2表达比值上调,而对照组和佐剂组未见明显改变。结论 内耳免疫反应可诱导细胞凋亡发生, Bcl 2和Bax蛋白在其中起了重要调节作用。     

内耳免疫反应中细胞凋亡及Caspase-3动态表达的研究

目的:研究内耳免疫反应过程中是否存在细胞凋亡,以及细胞凋亡是否与Caspase3信号转导有关。方法:选用雌性白色豚鼠45只,随机分为实验组29只,对照组16只,以钥孔虫戚血蓝蛋白(KLH)全身免疫后,实验组以相同抗原进行内耳免疫,对照组内耳注射等量的磷酸盐缓冲生理盐水(PBS),分别在内耳免疫术后1、3、5、7d和14d后处死动物,于免疫前及处死前行双侧听性脑干反应(ABR)测试。取内耳免疫侧耳蜗做石蜡切片。通过DNA末端转移酶介导的缺口末端标记法(TUNEL)检测内耳凋亡细胞,免疫组织化学检测内耳Caspase3的表达。结果:实验组豚鼠内耳免疫前、后反应阈比较有统计学意义(P<0.05或P<0.01);对照组给药前、后比较反应阈无明显变化。实验组豚鼠内耳均存在TUNEL染色阳性细胞,并且TUNEL染色阳性细胞具有凋亡细胞的典型形态学特征,而对照组仅在支持细胞、血管纹和螺旋神经节细胞中发现极少数TUNEL染色阳性细胞。Caspase3免疫组织化学染色实验组内耳从内耳免疫后5d开始出现阳性表达,而对照组表达阴性。结论:内耳免疫反应可以诱导细胞凋亡的发生;内耳免疫反应诱导细胞凋亡的发生中有Caspase3的激活。     

实验性自身免疫性内耳病耳蜗热休克蛋白70的表达

目的　探讨自身免疫性内耳病模型动物耳蜗热休克蛋白的表达。方法　利用同种异体内耳抗原免疫豚鼠 ,以建立自身免疫性内耳病 (autoimmuneinnereardisease ,AIED)动物模型 ,并应用免疫组织化学及原位杂位技术 ,研究热休克蛋白 (heatshockprotein ,hsp) 70在正常对照组及AIED模型动物实验组耳蜗中的表达情况。结果　对照组豚鼠螺旋神经节细胞中存在hsp70样蛋白基础表达 ;实验组 2 8耳中 10耳 (35 7% )听阈提高≥ 10dB ;此组动物螺旋神经节细胞和血管纹、螺旋韧带hsp70及其mRNA表达明显增强。结论　以粗制膜迷路抗原免疫豚鼠 ,听阈提高动物hsp70在螺旋神经节细胞和血管纹、螺旋韧带合成增加。     

雏鸡基底乳头Fas蛋白表达与细胞凋亡的关系

目的 :研究耳毒性药物致雏鸡内耳损伤过程中细胞凋亡与Fas蛋白表达的关系。方法 :应用卡那霉素 10 0mg/ (kg·d)皮下注射 ,连续 10d ,建立雏鸡内耳损伤模型。在雏鸡内耳损伤后 1、3、7、14、2 1d采用免疫组化方法、TUNEL法 ,分别对基底乳头Fas蛋白免疫反应阳性细胞和凋亡细胞分布进行观察。结果 :TUNEL阳性细胞主要分布在雏鸡基底乳头腔面毛细胞层 ,较高水平标记发生在停药后第 7天 ,停药后第 14天 ,TUNEL阳性细胞开始减少。Fas蛋白表达从停药后第 1天开始增高 ,停药后第 3天表达水平达高峰 ,随后逐渐下降。结论 :Fas蛋白在雏鸡基底乳头损伤后的高水平表达与毛细胞凋亡紧密相关 ,可能参与了损伤过程中的毛细胞凋亡调控。     

豚鼠发育过程前庭上皮细胞增殖和凋亡的关系

目的 研究豚鼠胚胎正常发育过程中前庭上皮细胞增殖和细胞凋亡的变化，探讨两者之间的关系及在前庭终器发育中的作用。方法 选用不同发育期正常豚鼠20只，取前庭上皮组织切片，用免疫组化法检测增殖细胞核抗原（proliferation cell nuclear antigen,PCNA)，以末端脱氧核苷酸转移酶介导的生物dUTP缺口末端标记技术（TdT-mediatedd deoxyuridine triphosphate-biotin nick end labelling,TUNEL)和透射电镜观察细胞凋亡。结果 PCNA阳性细胞为支持细胞，毛细胞无阳性反应，随年龄增加，阳性细胞数逐渐减少。TUYNEL阳性反应也可发生于毛细胞和支持细胞，随年龄增加，阳性细胞数逐渐减少；出生后壶腹嵴阳性毛细胞位于其顶部。电镜下胚胎期毛细胞和支持细胞均可发生凋亡。结论 发育过程中，豚鼠内耳前庭上皮细胞增殖与细胞凋亡数目爱均逐渐减少，凋亡和增殖同时存在，自动调节正常细胞数目，与保证器官正常形态的发育相关。     

角蛋白、波形蛋白、神经细丝蛋白在人胎内耳的定位表达

本文对合法引产9～32周胎龄的人内耳中角蛋白、波形蛋白、神经细丝蛋白的表达进行了免疫组织化学定位研究。结果发现增殖期的前庭器和Corti器始基细胞均有这三种中间纤维的表达。随着内耳分化的进行，用蛋白表达部位限于表皮板、网板、支持细胞、血管纹和前庭壁细胞。波形蛋白的表达部位分布在Corti器始基细胞、一些支持细胞、环绕的结缔组织、软骨细胞、骨组织、血管纹缘细胞、螺旋神经节细胞和神经纤维，前庭感觉上度表达反应弱。神经细丝蛋白除了在神经细胞和神经纤维表达阳性外，在Corti器站基细胞上部、血管纹原始细胞表达明显，软骨细胞和骨组织表达弱。内耳发育成熟期，这三种中间纤维蛋白在感觉毛细胞和听毛细胞的内部都无阳性表达。研究结果提示：这三种中间纤维参与人内耳的发育，可能与人内耳功能的发生有关。     

氯化物协同转运蛋白KCC2在正常大鼠内耳中的表达及意义

目的 研究氯化物协同转运蛋白KCC2(potassium-chloride cotransporter-2)在内耳中的表达及分布.方法 用免疫荧光素FITC(异硫氰酸荧光素)标记的方法检测KCC2在正常大鼠内耳的分布,荧光素标记阳性部位揭示大鼠耳蜗内KCC2的分布情况.结果 KCC2的阳性表达部位主要分布在耳蜗的盖膜、柯蒂器、螺旋神经节细胞以及前庭壶腹嵴顶部的毛细胞,耳蜗螺旋韧带及血管纹上KCC2为弱阳性表达.结论 在正常大鼠的内耳中,KCC2在耳蜗和前庭中有表达,提示KCC2可能通过对K 、Cl-转运的控制,配合其它的离子通道共同维持淋巴液中K 、Cl-的离子平衡.     

Time course of inner ear degeneration and deafness in mice lacking the Kir4.1 potassium channel subunit

The Kir4.1 gene (KCNJ10) encodes an inwardly rectifying K(+) channel subunit abundantly expressed in the CNS. Its expression in the mammalian inner ear has been suggested but its function in vivo in the inner ear is unknown. Because diverse human hereditary deafness syndromes are associated with mutations in K(+) channels, we examined auditory function and inner ear structure in mice with a genetically inactivated Kir4.1 K(+) channel subunit. Startle response experiments suggest that Kir4.1-/- mice are profoundly deaf, whereas Kir4.1+/- mice react like wild-type mice to acoustic stimuli. In Kir4.1-/- mice, the Reissner membrane is collapsed, the tectorial membrane is swollen, and type I hair cells and spiral ganglion neurons as well as their central processes degenerate over the first postnatal weeks. In the vestibular ganglia, neuronal cell death with apoptotic features is also observed. Immunostaining reveals that Kir4.1 is strongly expressed in stria vascularis of wild-type but not Kir4.1-/- mice. Within the spiral ganglion, Kir4.1 labeling was detected on satellite cells surrounding spiral ganglion neurons and axons. We conclude that Kir4.1 is crucial for normal development of the cochlea and hearing, via two distinct aspects of extracellular K(+) homeostasis: (1). in stria vascularis, Kir4.1 helps to generate the cochlear endolymph; and (2). in spiral and vestibular ganglia, Kir4.1 in surrounding glial cells helps to support the spiral and vestibular ganglion neurons and their projecting axons.     

Expression of heat shock protein 70 in immune response of the guinea pig inner ear]

OBJECTIVE: To explore whether the immune response of the inner ear could induce heat shock protein (hsp) 70 in guinea pig cochlea. METHODS: A model of autoimmune inner ear disease (AIED) was established by systemically immunizing the guinea pig with the homologous crude inner ear antigen (CIEAg). The immunized cochleae and normal control cochleae were examined for the expression of hsp70 with techniques of immunohistochemistry and in situ hybridization. RESULTS: In the control animals, the expression of the hsp70-like protein appeared only in the spiral ganglion, whereas in the cochleae with CIEAg immunization, strong expression of the hsp70-like protein and its mRNA appeared in the spiral ganglion as well as in the stria vascularis and the spiral ligament. The hearing thresholds were significantly increased in 10 out of 28 cochleae (35.7%) with CIEAg immunization. CONCLUSION: The results suggest that the immune response of the inner ear can induce the expression of hsp70 in the guinea pig cochlea.     

Relationship between three inner ear antigens with different molecular weights and autoimmune inner ear disease

Crude inner ear antigen (CIEAg) can induce autoimmune inner ear disease (AIED) although it is not known which subcomponent of CIEAg is involved. In this study, we investigated the relationship between 3 purified inner ear antigens (31, 42-45 and 60 kD proteins) and AIED, and determined their distribution in normal guinea pig cochlea. Three groups of guinea pigs were immunized with the three inner ear antigens and one group served as a control. The hearing thresholds, serum IgG level and morphological changes in the inner ear were observed. The expression of the three antigens in the cochlea was detected using immunohistochemical techniques. No obvious changes in hearing thresholds or inner ear morphology were observed between the control and 42-45 kD groups. Animals immunized with the 31 or 60 kD proteins showed a significant increase in hearing thresholds (p < 0.05 vs control), accompanied by morphological changes in the inner ear. The serum IgG level was increased significantly (p < 0.05) in all immunized animals. The 31 kD protein was distributed in the cochlear nerve and spiral ganglion, while the 42-45 and 60 kD proteins were distributed widely, being found in the spiral ganglion, organ of Corti, stria vascularis and spiral ligament. These results suggest that two subcomponents of CIEAg (the 31 and 60 kD proteins) may induce AIED independently, that several inner ear antigens may contribute to the pathogenesis of AIED and that the 31 kD protein is of high tissue specificity and may be used as a marker protein for the clinical diagnosis of AIED.     

Histopathological morphometric study of cochleosaccular dysplasia in Dalmatian dogs

Objective

To analyze temporal bones of deaf Dalmatian dogs from 5 days after birth to adulthood to better understand the pathogenesis of cochleosaccular dysplasia.

Methods

This is an experimental animal histopathological temporal bone study that included two groups of temporal bones. Group I consisted of 41 temporal bones from deaf Dalmatian dogs and group II of 25 temporal bones from 15 “normal” aged-matched, hearing Black Labradors. Morphometric analysis included: stria vascularis and spiral ligament area measurements, and cell counts of spiral ganglion, Scarpa's ganglion, and hair cells of saccular macula.

Results

The following findings were significantly less in deaf Dalmatian group compared to hearing Labradors: (1) cellular area of the stria vascularis in all cochlear turns; (2) cellular area of spiral ligament in the inferior part of the basal turn; (3) cellular density of spiral ganglion cells within segments III and IV; (4) number of Scarpa's ganglion cells; and (5) density of saccular hair cells types I and II. A borderline negative correlation was found between average density of spiral ganglion cells of segments III and IV and age in group I. Young deaf animals showed some cochlear hair cells, however in adult dogs all hair cells were replaced by supporting cells.

Conclusion

General pattern of cochleosaccular dysplasia is variable, even when only one etiology, the genetic one, is involved. The gradual degeneration of inner ear elements in the cochleosaccular degeneration might indicate that early intervention might be crucial to stop the progression of cochleosaccular dysplasia.     

正常豚鼠内耳水通道蛋白的表达及意义

目的：检测正常豚鼠内耳组织中水通道蛋白（aquaporins,AQPs）的表达,探讨其在内耳液体平衡中的意义.方法：用免疫组织化学方法,以兔抗大鼠AQP0、1、2、3、5、7、8的多克隆抗体,检测正常豚鼠内耳组织中水通道蛋白亚型0、1、2、3、5、7、8的表达.结果：水通道蛋白亚型0、1、2、3、5、7、8在豚鼠内耳有不同程度、不同模式的表达,其中AQP0仅在血管纹上皮细胞、螺旋神经节细胞有较弱的表达,AQP1的分布见于包绕骨迷路、内淋巴囊、内淋巴管的纤维细胞,基底膜鼓阶面细胞、螺旋韧带纤维细胞、螺旋缘纤维细胞、Corti器、内外螺旋沟、血管纹、椭圆囊壁、球囊壁、螺旋神经节细胞等.AQP2表达在血管纹、Corti器、螺旋神经节细胞和内淋巴囊中.AQP3、7、8的分布类似,在螺旋神经节和包绕膜迷路的组织中均有表达,其中Corti器、内外螺旋沟、血管纹、螺旋神经节表达较强,在螺旋韧带、螺旋缘纤维细胞表达较弱.AQP5则在Corti器、内外螺旋沟、螺旋神经节细胞表达较强,在螺旋韧带纤维细胞表达稍弱.结论：在正常豚鼠内耳中,尤其是膜迷路中有多种水通道蛋白亚型,以不同的方式表达,他们可能在维持膜迷路液体平衡中起着协同作用.     

Anti-clarin-1 AAV-delivered ribozyme induced apoptosis in the mouse cochlea

Usher syndrome type 3 is caused by mutations in the USH3A gene, which encodes the protein clarin-1. Clarin-1 is a member of the tetraspanin superfamily (TM4SF) of transmembrane proteins, expressed in the organ of Corti and spiral ganglion cells of the mouse ear. We have examined whether the AAV-mediated anti-clarin ribozyme delivery causes apoptotic cell death in vivo in the organ of Corti. We used an AAV-2 vector delivered hammerhead ribozyme, AAV–CBA–Rz, which specifically recognizes and cleaves wild type mouse clarin-1 mRNA. Cochleae of CD-1 mice were injected either with 1 μl of the AAV–CBA–Rz, or control AAV vectors containing the green fluorescent protein (GFP) marker gene (AAV–CBA–GFP). Additional controls were performed with saline only. At one-week and one-month post-injection, the animals were sacrificed and the cochleae were studied by histology and fluorescence imaging.

Mice injected with AAV–CBA–GFP displayed GFP reporter expression of varying fluorescence intensity throughout the length of the cochlea in the outer and inner hair cells and stria vascularis, and to a lesser extent, in vestibular epithelial cells. GFP expression was not detectable in the spiral ganglion. The pro-apoptotic effect of AAV–CBA-delivered anti-clarin-1 ribozymes was evaluated by TUNEL-staining. We observed in the AAV–CBA–Rz, AAV–CBA–GFP and saline control groups apoptotic nuclei in the outer and inner hair cells and in the stria vascularis one week after the microinjection. The vestibular epithelium was also observed to contain apoptotic cells. No TUNEL-positive spiral ganglion neurons were detected. After one-month post-injection, the AAV–CBA–Rz-injected group had significantly more apoptotic outer and inner hair cells and cells of the stria vascularis than the AAV–CBA–GFP group.

In this study, we demonstrate that AAV–CBA mediated clarin-1 ribozyme may induce apoptosis of the cochlear hair cells and cells of the stria vascularis. Surprisingly, we did not observe apoptosis in spiral ganglion cells, which should also be susceptible to clarin-1 mRNA cleavage. This result may be due to the injection technique, the promoter used, or tropism of the AAV serotype 2 viral vector. These results suggest the role of apoptosis in the progression of USH3A hearing loss warrants further evaluation.     

Molecular biology of hearing

The inner ear is our most sensitive sensory organ and can be subdivided into 3 functional units: organ of Corti, stria vascularis and spiral ganglion. The appropriate stimulus for the organ of hearing is sound which travels through the external auditory canal to the middle ear where it is transmitted to the inner ear. The inner ear habors the hair cells, the sensory cells of hearing. The inner hair cells are capable of mechanotransduction, the transformation of mechanical force into an electrical signal, which is the basic principle of hearing. The stria vascularis generates the endocochlear potential and maintains the ionic homeostasis of the endolymph. The dendrites of the spiral ganglion form synaptic contacts with the hair cells. The spiral ganglion is composed of neurons that transmit the electrical signals from the cochlea to the central nervous system. In the past years there was significant progress in research on the molecular basis of hearing. More and more genes and proteins which are related to hearing can be identified and characterized. The increasing knowledge on these genes contributes not only to a better understanding of the mechanism of hearing but also to a deeper understanding of the molecular basis of hereditary hearing loss. This basic research is a prerequisite for the development of molecular diagnostics and novel therapies for hearing loss.     

Distribution of beta-tubulin in guinea pig inner ear

Our previous research had suggested that beta-tubulin might be an autoantigen for autoimmune inner ear disease. In this study, the expression of beta-tubulin in inner ears of normal and tubulin-immunized guinea pigs was examined by immunohistochemical staining. Strong immunoreactivity to beta-tubulin monoclonal antibody was found in stria vascularis, neurons of the spiral ganglion, cochlear nerve fibers and spiral ligament. Diffuse staining was found in the stria vascularis and the neurons of the spiral ganglion, while dense network staining was found in the spiral ligament, the nerve fibers and the vestibular end organs. The semicircular canals, endolymphatic duct and sac were also positively stained. In inner ears of guinea pigs challenged with beta-tubulin, staining intensity was diminished in the stria vascularis, the spiral ligament, and the neurons of the spiral ganglion. The results suggest that beta-tubulin is distributed to most structures of guinea pig inner ear. A challenge to the inner ear by tubulin could change the beta-tubulin distribution and cause degeneration in the spiral ganglion. The results support the hypothesis that beta-tubulin might be an autoantigen for autoimmune inner ear disease.