Acute salivary gland hypofunction in the duct ligation model in the absence of inflammation

Objective:  The commonly associated aetiology of salivary gland inflammation and salivary hypofunction has led to the widely held belief that inflammation causes salivary gland hypofunction. Indeed, our own recent study seemed to support this contention. Here, we tested the hypothesis that, in an acute duct ligation model, eliminating inflammation the submandibular gland would recover normal function.
Materials and methods:  Ligation of the rat submandibular gland excretory duct for 24 h was used to induce inflammation and salivary gland hypofunction. A group of duct ligated rats was compared with a second group given dexamethasone, on the day of duct ligation. Twenty-four hours later salivary gland function was assessed and salivary glands were collected.
Results:  Histology and myeloperoxidase activity assay revealed a profound decrease in inflammatory cell infiltration of ligated glands from rats given dexamethasone, compared with ligated glands in the absence of dexamethasone. Salivary flow rate evoked by methacholine was decreased ( P  < 0.01) by approximately 56% (ligated vs control, 79 ± 9  μ l min⁻¹ g⁻¹ vs 177 ± 11  μ l min⁻¹ g⁻¹) and salivary flow from ligated dexamethasone-treated and ligated glands was similar.
Conclusion:  Despite eliminating the inflammatory reaction in the ligated gland, salivary hypofunction was not reversed, suggesting that other mechanisms must be at work in the ligation-induced salivary hypofunction.     

干燥综合征动物模型建立及病理变化的初步探讨

目的建立人类干燥综合征的动物模型,试图模拟其唾液腺的病理变化。方法运用同种鼠的颌下腺组织诱导类似于人类干燥综合症（ＳＳ）唾液腺表现的动物模型。结果不同品系鼠和不同抗原量组颌下腺淋巴细胞浸润程度不同,Ｃ５７品系鼠（注射抗原浓度５００μｇ／ｍｌ和７５０μｇ／ｍｌ组）浸润程度较明显;而饮水量与浸润淋巴细胞程度间无相关关系。结论初步建立了类似于人类ＳＳ表现的鼠动物模型,为进一步完善ＳＳ的动物模型提供了一定的基础     

Epiregulin is critical for the acinar cell regeneration of the submandibular gland in a mouse duct ligation model

Acinar cell regeneration from tubular structures has been reported to occur in duct‐deligated salivary glands. However, the detailed process of acinar cell regeneration has not been clarified. We have developed a mouse duct ligation model to clarify the mechanisms underlying acinar cell regeneration, and we analyzed the epidermal growth factor receptor (EGFR) and epidermal growth factor (EGF) ligands using the model. We studied these ligands expressions in the course of acinar cell regeneration using immunohistochemistry and RT‐PCR methods. In the duct‐ligated portion of the submandibular gland (SMG) that underwent atrophy, newly formed acinar cells were observed arising from the tubular structures after the release of the duct obstruction. The constitutive expression of EGFR was observed by immunohistochemistry in both the duct‐ligated and duct‐deligated animals as well as in normal controls. The EGFR phosphorylation detected on the tubular structures after duct ligation paralleled the acinar cell regeneration. RT‐PCR showed an increase in the epiregulin and heparin‐binding EGF levels from day 0 to day 3 after the release of the duct obstruction. The EGF level was increased only after day 7. In vitro, cultured cells isolated from ligated SMGs proliferated and produced EGF ligands following the addition of epiregulin to the culture medium. These findings suggest that the tubular structures localized in an atrophic gland are the source of acinar cell regeneration of the salivary gland. The induction of EGF ligands, in particular epiregulin, may play an important role in acinar cell regeneration in this model.     

Sialographic images of pathological changes in the mouse parotid gland

In order to correlate pathological changes of mouse parotid glands with their sialographic images, we conducted studies on mice with known pathological changes: mice with Stensen's duct ligated, NZB mice with a systemic auto-immune disease, and aged mice. The sialographic images were found to be specific for the pathological changes: The glands after ligation of Stensen's duct were characterized by dilated, large excretory ducts with a reduced system of peripheral ducts; the glands of NZB mice showed lobular leakage of the contrast medium from small excretory ducts; and the glands of aged mice showed a great reduction in the ductal system. It is concluded that sialography yields useful information on the pathological changes of the ductal systems in the mouse parotid gland.     

腮腺主导管结扎后腺体的组织学变化

目的:探讨腮腺导管结扎后腺体组织的生物学变化.方法:用SD大鼠建立动物模型,将其右侧腮腺主导管结扎;定期获取标本,制备组织切片,利用苏木精-伊红染色、免疫组织化学染色及形态计量等方法,观察术后不同阶段腮腺组织中腺泡、肌上皮细胞、导管及间质的形态变化及体积分数.结果:腮腺主导管结扎后,腺体组织开始萎缩,其中腺泡体积分数逐...     

A comparative study of the role of atresia and stenosis of the outflow duct of a salivary gland in the pathogenesis of dystrophic and inflammatory changes]

Experiments were carried out with submandibular salivary glands of 20 dogs. Complete obturation of the submandibular duct (in 10 animals) was achieved by binding this duct. Partial impairment of the saliva flow from the gland was induced in 10 animals by fixing a metal ring on the duct. The experiment has demonstrated that both complete and partial obturation of the salivary duct result in the development of chronic sialadenitis. Partial obturation of salivary outflow from the gland did not result in an acute inflammation but in a flaccid process, slowly developing dystrophic changes in acinar cells, gradually developing sclerosis of the glandular parenchyma and stroma. These data indicate a direct relationship between the intensity of dystrophic changes in the salivary gland and the severity of impairment of salivary discharge.     

B7-H3在涎腺肿瘤和炎症中的表达

目的 研究B7-H3在涎腺良、恶性肿瘤组织和涎腺炎症中的表达特征.方法 聚合酶链反应(PCR)、反转录聚合酶链反应(RT-PCR)、免疫组化检测B7-H3 mRNA和蛋白在涎腺良、恶性肿瘤组织、炎症组织和正常涎腺组织中的表达.结果 PCR结果显示,B7-H3在涎腺良、恶性肿瘤组织、炎症组织和正常涎腺组织中均有表达.RT-PCR结果显示,与涎腺正常组织组比较,良性肿瘤组B7-H3 mRNA表达量为其4.2106倍,显著高于涎腺正常组织组(P<0.05);恶性肿瘤组为其3.216倍,也高于涎腺正常组织组(P<0.05):涎腺炎症组为1.812倍,但差异无统计学意义(P>0.05).免疫组化结果显示,良性肿瘤和恶性肿瘤中B7-H3的表达差异性具有统计学意义(P< 0.05),而在炎性组织中的B7-H3表达差异无统计学意义(P>0.05).结论 涎腺肿瘤组织B7-H3 mRNA和蛋白表达显著高于正常涎腺组织:涎腺炎症组织B7-H3表达与在涎腺正常组织中表达差异无统计学意义.     

Epidermal growth factor in the submandibular salivary glands of congenitally athymic mice.

The submandibular salivary glands of a group of congenitally athymic (“nude”) mice were assayed for their epidermal growth factor (EGF) content and their histology was examined by light microscopy. The ability of the submandibular salivary glands from athymic mice to respond to an androgenic agent was assessed. The histology of the submandibular salivary glands resembled that of normal mice. Athymic mice had concentrations of EGF in their submandibular salivary glands which were similar to those reported previously for normal mice As in normal mice, male athymic mice had more prominent granular convoluted tubules than female mice, but, as in normal mice, testosterone treatment of female athymic mice resulted in an increase in both the EGF content and in the number of granules within the cells of the granular tubules of the duct system of the submandibular salivary gland.These results provide no evidence for a relationship between the level of submandibular salivary gland EGF and the immunological deficiency of nude mice, and show that the abnormalities in development of nude mice do not extend to their submandibular salivary glands.     

Acceleration of rat salivary gland tissue repair by basic fibroblast growth factor

A model of atrophic rat submandibular gland was used to examine the ability of basic fibroblast growth factor (bFGF) to accelerate tissue repair. The gland duct was separated carefully from associated blood vessels and nerve, and ligated with a 8-0 suture under a surgical microscope. Two weeks after ligation, the glandular tissue showed severe atrophy and weight loss (to 26% of that in a sham-operated group). Thereafter, the ligature was removed and various amounts of bFGF, isoproterenol or saline were instilled retrogradely through the duct. Both isoproterenol and bFGF increased cell proliferation significantly. bFGF accelerated the proliferation of various cell types, including both acinar and ductal. The proliferative effects of bFGF peaked at a dose of 1 ng/gland. When bFGF (1 ng/gland) was administered to the atrophic gland, its weight increased to 125% of the glands in saline-treated control animals after 2 weeks. The effects of bFGF were also examined in normal submandibular glands: bFGF stimulated cell proliferation, but the effective concentration was at least 50 times higher than that required in the atrophic gland. The results from immunohistochemical tests against anti-FGF receptor-type 1 antibody demonstrated increased immunoreactivity in the damaged gland, which might be involved in the difference in the response to bFGF between damaged and normal glands. Overall, the results indicate that bFGF can accelerate tissue repair in salivary gland.     

Root resorption associated with orthodontic force in inbred mice: genetic contributions

Root resorption (RR) is an unwanted sequela of orthodontic treatment. Despite rigorous investigation, no single factor or group of factors that directly causes RR has been identified. The purpose of this study was to examine the effect of the genotype on susceptibility or resistance to develop RR secondary to orthodontic force. Nine-week-old male mice from eight inbred strains were used and randomly distributed into control (C) or treatment (T) groups as follows: A/J (C = 9,T = 9), C57BL/6J (C = 7,T = 8), C3H/HeJ (C = 8,T = 6), BALB/cJ (C = 8,T = 6), 129P3/J (C = 6,T = 8), DBA/2J (C = 8,T = 9), SJL/J (C = 8,T = 10), and AKR/J (C = 9,T = 8). Each of the treated mice received an orthodontic appliance to tip the maxillary left first molar mesially for 9 days. Histological sections of the tooth were used to determine RR and tartrate resistant acid phosphatase (TRAP) activity. The Wilcoxon ranked-sum non-parametric test was used to evaluate differences between the groups. The results showed that the DBA/2J, BALB/cJ, and 129P3/J inbred mouse strains are highly susceptible to RR, whereas A/J, C57BL/6J and SJL/J mice are much more resistant. The variation in the severity of RR associated with orthodontic force among different inbred strains of mice when age, gender, food, housing, and orthodontic force magnitude/duration are controlled support the hypothesis that susceptibility or resistance to RR associated with orthodontic force is a genetically influenced trait.     

Hypoglycaemic effects of salivary duct ligation upon diabetes mellitus in mice.

The effects of bilateral ligation of the ducts of the submandibular gland or the parotid gland alone or of both glands upon blood sugar levels were investigated in adult male non-diabetic Connought Swiss, non-diabetic and streptozotocin-induced diabetic C57BL/6J and mutant-diabetic C57BL/KsJ-db/db mice. The hypoglycaemic effect was only consistent and significant when both the parotid and submandibular ducts were simultaneously ligated bilaterally. This effect was most pronounced in mutant-diabetic mice. The mechanism of this effect is discussed with regard to the possible existence of an insulin-antagonist produced in the submandibular gland.     

锥形束CT在颌下腺结石诊断中的应用

目的:探讨锥形束CT(CBCT)对颌下腺结石的临床诊断价值。方法:利用CBCT的影像诊断系统对9例颌下腺肿大患者的下颌下区进行轴面、冠状面、矢状面及三维重建影像检查,同时进行测量分析。结果:8例患者经手术治疗后确定的结石大小、位置,与CBCT检查结果一致,1例术前自行排石。结论:CBCT对颌下腺结石有较高的诊断价值,能确定结石的数目、大小并定位,准确性高,为临床手术治疗提供直接依据。     

Murine autoimmune exocrinopathy: the minor salivary gland network shows a dichotomous pattern of histopathologic involvement

The minor salivary gland network of the MRL/1 mouse was investigated in a kinetic study and compared with the major submandibular gland. We report that minor salivary glands adopt two mutually exclusive patterns of inflammatory lesions depending on the gland. The first pattern is characteristic of human Sjogren's syndrome. It developed during the second month, affected 89% of the animals over 20 weeks old, and consisted of an accumulation of mononuclear cells around the duct system. Only the anterior buccal gland (ABG) showed this pattern, which is shared by the major salivary glands. The ratio of CD44+ to CD8+ cells was the same in lesions and in healthy tissue. No neutrophils were found in these lesions. The second pattern affected all the minor salivary glands except the ABG. These lesions were never observed before the age of 20 weeks and affected 38% of MRL/1 mice between the ages of 10–32 weeks. In this pattern, neutrophils were frequently found, but mainly gathered at the periphery of the gland lobules. That a systemic immunoregulatory defect may be expressed as two different patterns of histopathology in the minor salivary glands suggest that the network behaves as a dichotomous entity depending on particular microenvironmental influences.     

Study on factors that affect caries susceptibility in mice

In our previous research, we discovered a C57BL/6CrSlc mouse strain (B6) that is highly susceptible to caries and a C3H/HeSlc mouse strain (C3H) that is highly resistant to caries, and reported that genetic factors play a role in caries susceptibility. In a study on the B6 and C3H mouse strains, a difference was found in their saliva flow rates, as well as their caries scores. In the present study, we focused on saliva secretion, which may influence differences in caries susceptibility. We examined temporal changes in stimulated saliva secretion volume in B6 and C3H mice, and found that secretion volume was significantly higher in C3H mice than in B6 mice even at 30 min after stimulation, and that total saliva volume was significantly higher in C3H mice. In addition, histological comparisons of the submandibular gland in the two strains revealed the ratio of acinar cells area to be significantly higher in C3H mice than in B6 mice. We then examined the gene expression of the muscarinic acetylcholine receptors M1R, M2R and M3R, which are thought to be regulatory factors of water secretion from acinar cells in the parasympathetic nervous system, but did not find any significant differences between the two strains. Enamel hardness was significantly higher in C3H mice than in B6 mice. The acinar cell ratio in the submandibular gland may be a factor associated with differences in salivary flow rate, and enamel hardness may be a determining factor of tooth decalcification; two factors that affect caries susceptibility.     

Induction of Sca-1 in the duct cells of the mouse submandibular gland by obstruction of the main excretory duct

The effect of ligation of the main excretory duct (MED) of the mouse submandibular gland (SMG) on the expression of Sca-1, a stem cell antigen, was examined by Western blotting and immunohistochemistry. By Western blotting, the expression of Sca-1 with a molecular weight of 18 kDa was identified in the normal gland. At 1 day post-ligation, the expression level of Sca-1 was strongly increased in the experimental gland and weakly in the contralateral gland, and such expression in both glands decreased at 6 days. By immunohistochemistry, Sca-1 was detected weakly in the apical membrane of excretory duct (ED) cells of the SMG under the normal condition. By duct ligation, Sca-1 became expressed strongly in most cells of the two major duct systems, i.e., the striated duct (SD) and granular convoluted tubules (GCT), but was not detected in the acinar (Ac) cells. By fluorescence-activated cell sorter (FACS) analysis, the number of side population (SP) cells in this gland was found to be increased by ligation. These results imply that Sca-1-positive cells may have a role in the duct cell proliferation in the regeneration step elicited by MED ligation-induced injury.     

应用聚合酶链反应技术检测腮腺腺淋巴瘤中EB病毒整合

目的 研究腮腺腺淋巴瘤（Ｗａｒｔｈｉｎ’ｓ瘤）和ＥＢ病毒感染之间的关系。方法 应用聚合酶链反应技术检测７５例Ｗａｒｔｈｅｒ’ｓ瘤,２０例正常腮腺组织的ＥＢ病毒ＤＮＡ整合情况,结果：６２例单发Ｗａｒｔｈｉｎ’ｓ瘤中１９例检出ＥＢ病毒ＤＮＡ整合,１３例双侧或单侧多发Ｗａｒｔｈｅｒ’ｓ瘤中９例检测出ＥＢ病毒ＤＮＡ整合,２０例正常腮腺组织中３例ＥＢ病毒ＤＮＡ整合阳性,结论 ＥＢ病毒感染与双侧或单侧多发Ｗａ     

Expression of kallikrein-related peptidase 4 in dental and non-dental tissues

Kallikrein-related peptidase 4 (KLK4) is critical for proper dental enamel formation. Klk4 null mice, and humans with two defective KLK4 alleles have obvious enamel defects, with no other apparent phenotype. KLK4 mRNA or protein is reported to be present in tissues besides teeth, including prostate, ovary, kidney, liver, and salivary gland. In this study we used the Klk4 knockout/NLS-lacZ knockin mouse to assay Klk4 expression using β-galactosidase histochemistry. Incubations for 5 h were used to detect KLK4 expression with minimal endogenous background, while overnight incubations susceptible to false positives were used to look for trace KLK4 expression. Developing maxillary molars at postnatal days 5, 6, 7, 8, and 14, developing mandibular incisors at postnatal day 14, and selected non-dental tissues from adult wild-type and Klk4(lacZ/lacZ) mice were examined by X-gal histochemistry. After 5 h of incubation, X-gal staining was observed specifically in the nuclei of maturation-stage ameloblasts in molars and incisors from Klk4(lacZ/lacZ) mice and was detected weakly in the nuclei of salivary gland ducts and in patches of prostate epithelia. We conclude that KLK4 is predominantly a tooth-specific protease with low expression in submandibular salivary gland and prostate, and with no detectable expression in liver, kidney, testis, ovary, oviduct, epididymis, and vas deferens.     

牙龈卟啉单胞菌基因疫苗pcDNA3.1(+)/kgpcd免疫原性研究

目的:研究重组质粒pcDNA3. 1( ) /kgpcd免疫原性,并观察目的基因编码的蛋白在小鼠肌肉及颌下腺组织中的原位表达情况。方法:重组质粒pcDNA3. 1 ( ) /kgpcd经肌肉注射和颌下腺区注射免疫BALB/c小鼠,采用间接ELISA方法检测免疫后BALB/c小鼠血清中IgG和唾液中sIgA抗体水平;用免疫组织化学染色观察目的基因编码的蛋白在小鼠组织中的表达。结果:重组质粒经肌肉注射免疫可产生高水平的特异性血清IgG抗体,颌下腺区注射可同时诱导高水平的唾液中sIgA和血清中IgG抗体;骨骼肌、颌下腺导管内、腺泡腔内可见阳性着色。结论:重组质粒pcDNA3. 1( ) /kgpcd经颌下腺注射可同时诱导黏膜免疫和全身免疫应答,可作为有效免疫原,这为免疫牙周炎模型定菌鼠实验提供了依据。     

Establishment of ex vivo mucocele model using salivary gland organ culture

A mucocele is a common lesion originating from the minor salivary glands and frequently seen in children. For this study, we established an ex vivo mucocele model using a mouse salivary gland organ culture method.ResultsFirst, medium from the upper portion of salivary gland organ cultures was either removed or not, then culturing was continued for 10 days. After that 10-day period, 13 of 21 specimens (61.9%) in the medium removed group showed mucocele-like mucus restoration, while only 1 of 15 (6.7%) in the non-medium removed group showed restoration. Next, we examined mucocele type in the ex vivo salivary gland organ cultures and found mucous retention type mucocele formation in only the main duct of most of the cultures. Other types were observed in the main excretory and intercalated ducts, but not exclusively in the intercalated duct. We also investigated the effect of duct cutting on mucocele recrudescence. Mucoceles that developed in the cultures were cut with stainless needles under a stereomicroscope and mucus was promptly discharged. At 7 days after duct cutting, 5 of 19 specimens (26.3%) showed recrudescence mucus retention.ConclusionsThis is the first report of establishment of an ex vivo pathogenic condition for examination of salivary glands. Our model may be useful to establish mucocele treatment options including drug screening and surgical procedures.