Salivary Gland Damage Research Articles

OP061: Adipose tissue-derived mesenchymal stem cells for regeneration of irradiation-induced salivary gland damage

Cell-based therapy has been reported to repair or restore damaged salivary gland (SG) tissues after irradiation. This study was aimed at determining whether systemic administration of human adipose-derived mesenchymal stem cells (hAdMSCs) could ameliorate radiation-induced SG damage following irradiation. External irradiation at a dose of 15 Gy was administered to neck fields of C3H mice. Mice were administered with hAdMSCs through the tail vein immediately after irradiation, and this infusion was repeated once a week for three consecutive weeks. The administration of hAdMSCs had improved SFR at 12 weeks after irradiation. hAdMSC-transplanted SGs showed fewer damaged and atrophied acinar cells compared with the irradiated untreated group. TUNEL and PCNA assays revealed fewer apoptotic cells and increased proliferative indices in the hAdMSC group compared with the irradiated group. The injected hAdMSCs were detected in the transplanted SGs 4 weeks after transplantation. Transdifferentiation of hAdMSCs into acinar or ductal cells in vivo was also observed. This study suggests that hAdMSCs have the potential for protection against irradiation-induced cell loss as well as for transdifferentiation into salivary epithelial cells. hAdMSCs could be a candidate for cell-based therapy for restoration of radiation-induced SG damage.

CLINICAL AND ULTRASONOGRAPHIC CHARACTERISTICS OF SALIVARY MUCOCELES IN 13 DOGS

Salivary mucocele is one of the causes of submandibular swelling in dogs and is due to a collection of mucoid saliva that has leaked from a damaged salivary gland. The purpose of this case series report was to describe the clinical and ultrasonographic characteristics of confirmed salivary mucoceles in 13 dogs admitted to the Faculty of Veterinary Medicine at Cairo University. The final diagnosis of salivary mucocele was based on aspirate cytology for all dogs and additional surgical excision for seven dogs. For dogs admitted from 2 weeks to 1 month from the onset of clinical signs, the cervical mucocele appeared as a round echogenic structure with a large volume of central anechoic content. The wall was a clearly identified hyperechoic structure surrounding the gland. For dogs admitted between 1 to 2 months from the onset of clinical signs, the volume of anechoic material appeared less than that seen in the acute cases. The overall appearance of the salivary mucocele was heterogenous. For dogs admitted after 2 months from the onset of clinical signs, the salivary mucocele appeared grainy or mottled, with a heterogenous appearance and a further decrease in anechoic content. For one dog that presented after 3 months from the onset of clinical signs, the salivary mucocele was hard on palpation and appeared hyperechoic with distal acoustic shadowing. Findings from this study indicated that ultrasonographic characteristics of salivary mucoceles in dogs vary depending on the chronological stage of the disease.

Loss of TRPM2 function protects against irradiation-induced salivary gland dysfunction

Xerostomia as a result of salivary gland damage is a permanent and debilitating side effect of radiotherapy for head and neck cancers. Effective treatments for protecting, or restoring, salivary gland function are not available. Here we report that irradiation treatment leads to activation of the calcium-permeable channel, transient potential melastatin-like 2 (TRPM2), via stimulation of poly-ADP-ribose polymerase. Importantly, irradiation induced an irreversible loss of salivary gland fluid secretion in TRPM2+/+ mice while a transient loss was seen in TRPM2-/- mice with >60% recovery by 30 days after irradiation. Treatment of TRPM2+/+ mice with the free radical scavenger Tempol or the PARP1 inhibitor 3-aminobenzamide attenuated irradiation-induced activation of TRPM2 and induced significant recovery of salivary fluid secretion. Furthermore, TPL (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl) induced complete recovery of function in irradiated TRPM2-/- mice. These novel data demonstrate that TRPM2 is activated by irradiation, via PARP1 activation, and contributes to irreversible loss of salivary gland function.

Protective effects of resveratrol on salivary gland damage induced by total body irradiation in rats

One of the most common acute side effects of irradiation is xerostomia, which results from damage to the salivary gland cells by direct ionization. Resveratrol is a natural compound with profound anti-inflammatory and antioxidant properties. The purpose of the present study was to investigate the potential protective effects of resveratrol on injury to the salivary glands of rats that were exposed to total body irradiation. An experimental study at the Inonu University School of Medicine. Twenty-nine female rats were randomized into four groups: group 1, high-dose (100 mg/kg) resveratrol group (n = 7); group 2, low-dose (10 mg/kg) resveratrol group (n = 7); group 3, control (vehicle) rats (n = 7); and group 4, sham-irradiation group (n = 8). The medications were administered as single doses, and the rats were exposed to total body irradiation 24 hours after the treatment. The animals were sacrificed the following day, and the parotid and submandibular glands were excised. Salivary gland histology and the tissue levels of glutathione (GSH), nitric oxide (NO), and malondialdehyde (MDA) were investigated. The rats in group 1 showed significantly decreased acinar loss and less ductal damage and cell necrosis than those of the control group (P < .05). Antioxidant GSH levels were significantly increased by high doses of resveratrol treatment. The tissue activities of MDA in both the parotid and submandibular glands were significantly reduced in group 1. Low-dose resveratrol treatment did not significantly alter the tissue levels of MDA. Resveratrol at relatively high doses can reduce the irradiation-dependent salivary gland damage, suggesting that this natural antioxidant may be effectively used to lessen the side effects related to salivary gland dysfunction that is induced by irradiation.

Intraglandular transplantation of bone marrow-derived clonal mesenchymal stem cells for amelioration of post-irradiation salivary gland damage

External irradiation in head and neck cancers may induce irreversible hyposalivation and consequent xerostomia, stemming from radiation damage to salivary glands (SGs). As cell-based therapy has been reported to be able to repair or restore damaged SG tissues, we attempted to determine whether bone marrow-derived clonal mesenchymal stem cells (BM-cMSCs) can ameliorate irradiation-induced salivary gland damage via a murine model. External irradiation at a dose of 15Gy was delivered to the neck fields of C57BL/6 mice. We directly administered either homologous mouse BM-cMSCs labeled with PKH26 (treatment group) or PBS (control group) into SGs 24h after irradiation. Salivary flow rate (SFR) and lag time of salivation were measured at 12weeks after transplantation. At 4 and 12weeks post-transplantation, we performed morphological, histological, and immunofluorescent examinations. Transdifferentiation of administered BM-cMSCs into salivary epithelial cells was observed by confocal microscopy. SFR was significantly increased in BM-cMSCs-transplanted mice compared with PBS-injected mice at 12weeks after transplantation. Administration of BM-cMSCs preserved the microscopic morphologies of SGs, with more functional acini in BM-cMSC-transplanted SGs than in PBS-injected SGs. Immunofluorescent staining revealed less apoptotic cells and increased microvessel density in BM-cMSC-transplanted SGs compared with PBS-injected SGs. PKH-26 labeled BM-cMSCs were detected in transplanted SGs at 4weeks after transplantation and in vivo transdifferentiation of BM-cMSCs into acinar cells was also observed. This study suggests that BM-cMSCs can ameliorate salivary damage following irradiation and can be used as a source of cell-based therapy for restoration of irradiation-induced salivary hypofunction.

Microarray analysis of gene expression of bone marrow stem cells cocultured with salivary acinar cells

Our previous work has demonstrated that rat bone marrow stem cells (BMSCs) can transdifferentiate into α-amylase-producing cells after coculture with rat submandibular gland acinar cells. These transdifferentiated cells may be used for regeneration of damaged salivary gland. The purpose of this study was to investigate the global gene expression of rat BMSCs cocultured with rat submandibular gland acinar cells and the factors inducing this transdifferentiation. Rat BMSCs were indirectly cocultured with rat submandibular gland acinar cells by using the double chamber system for 5 and 10 days. The global gene expression of BMSCs during transdifferentiation into acinar cells was investigated by microarray analysis. A total of 45,018 probes were used and 41,012 genes were detected. After coculture for 5 days, 1409 genes were upregulated more than twofold and 1417 genes were downregulated more than twofold (p<0.005). Moreover, after coculture for 10 days, 1356 genes were upregulated more than twofold and 1231 genes were downregulated more than twofold (p<0.005). Bone morphogenetic protein (BMP)-6 was one of the top-ranked upregulated genes. The hub genes were interleukin-6 and CCAAT/enhancer-binding protein β (CEBPB) in the early and late response gene groups, respectively. This is believed to be the first study on the global gene expression of rat BMSCs cocultured with rat acinar cells. Many genes related to the function of salivary acinar cells such as those responsible for the production of α-amylase protein were upregulated and many genes related to the differentiation of BMSCs into adipocytes and osteoblasts were downregulated. In addition, BMP-6 gene was found to be highly upregulated. We proposed that three target genes, BMP-6, interleukin-6 and CEBPB, play important roles in the transdifferentiation of BMSCs into acinar cells, and are worthy of further investigation.

Molecular-Targeted and Cell-Based Therapies for Sjogren Syndrome

Sjogren’s syndrome (SS) is a systemic autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands, in particular the salivary and lachrymal glands. The etiology and pathogenic mechanisms of SS remain largely unknown. Accordingly there are no treatments that completely reverse the disease in patients. The purpose of this invited review is not to provide a comprehensive overview of treatment approaches for SS, but rather to comment on emerging molecular targeted therapies and cell-based therapies. Although a number of molecular-targeted therapies are currently available for autoimmune diseases, very few but Rituximab and Epratuzumab appear to be efficacious for patients with SS, suggesting the importance of an enhanced understanding of SS pathogenesis. Cell-based therapy has been demonstrated as a promising approach to treat salivary gland dysfunction in SS mouse models. Further assessment for functional restoration of damaged salivary glands in organotypic culture or in SS patients is necessary to translate the cellbased therapies into the clinic. Keywords: B-cell targeted therapies, bone marrow-derived cells (BMDCs), cell-based therapies, cytokines, epratuzumab, immunoproteasome, interferons (IFNs), molecular-targeted therapies, rituximab, tumor necrosis factor-alpha (TNF-α), sjogren’s syndrome, T-cell targeted therapies

The effects of heparan sulphate mimetic RGTA‐OTR4120 on irradiated murine salivary glands

This study focuses on the potential of ReGeneraTing Agent OTR4120 (RGTA-OTR4120) to treat radiation-induced damage of salivary glands. RGTAs are biopolymers designed to mimic the effects of heparan sulphate, thereby stimulation tissue repair and regeneration. C3H mice were irradiated with a single dose of 15 Gy in the head and neck region. RGTA-OTR4120 was injected 24 h after radiotherapy, followed by weekly injections. At 2, 6 and 10 weeks after radiotherapy, salivary flow rates were measured and animals were sacrificed to obtain parotid and submandibular glands for histology. Periodic acid Schiff stain was performed to visualize mucins that are produced by acinar cells. Amylase and total protein content were measured in saliva samples. Salivary flow rates were increased at 2 weeks, but not at 6 and 10 weeks after radiotherapy with RGTA-OTR4120 administration, compared to irradiated controls. Two and 10 weeks after radiotherapy, the mucin production activity of acinar cells was increased under influence of RGTA administration. RGTA-OTR4120 did not influence amylase or total protein secretion. RGTA-OTR4120 administration has a positive effect on salivary flow rates in irradiated mice on the short term. The effect was absent 10 weeks after radiotherapy, while at that time point, mucin producing activity of acinar cells was elevated by RGTA-OTR4120 administration. Given these results and the advantages of RGTA use in irradiated patients, further investigation on the potential of this drug to treat radiation-induced salivary gland damage, alone or in combination with other drugs, such as amifostine, is suggested.

Post-radiotherapy morphological changes of parotid gland are dose- and radiotherapy technique-dependent

Free AccessCorrespondencePost-radiotherapy morphological changes of parotid gland are dose- and radiotherapy technique-dependentM T C Ying, S C H Cheng, V W C Wu and D L W KwongM T C YingDepartment of Health Technology and Informatics, The Hong Kong Polytechnic University Hunghom, Kowloon, Hong Kong SAR, ChinaSearch for more papers by this author, S C H ChengDepartment of Health Technology and Informatics, The Hong Kong Polytechnic University Hunghom, Kowloon, Hong Kong SAR, ChinaSearch for more papers by this author, V W C WuDepartment of Health Technology and Informatics, The Hong Kong Polytechnic University Hunghom, Kowloon, Hong Kong SAR, ChinaSearch for more papers by this author and D L W KwongDepartment of Clinical Oncology, Queen Mary Hospital, The University of Hong Kong Pokfulam, Hong Kong SAR, ChinaSearch for more papers by this authorPublished Online:13 Feb 2014https://doi.org/10.1259/bjr/30087983SectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail AboutThe Editor,We would like to thank the author for providing the additional information on pre- and post-therapeutic assessment of submandibular glands in CT [1]. It is of great interest to know the time dependent changes of the submandibular glands following radiochemotherapy [1]. Regarding this, we would like to provide further information from our recent studies [2,3]. In investigating the sonographic appearances of parotid glands in two groups of patients (nasopharyngeal carcinoma (NPC) patients received intensity-modulated radiotherapy (IMRT) with parotid sparing, and NPC patients received conventional radiotherapy without parotid sparing) and healthy subjects, we found that parotid glands in patients treated with IMRT had a sonographic appearance similar to that in healthy subjects (i.e. usually hyperechoic, homogeneous and marginally seen intra-parotid ducts), while parotid glands in patients treated with conventional RT tended to be hypoechoic, heterogeneous and clearly seen intra-parotid ducts [2]. The result of this study shows that the sonographic appearance of the parotid gland in post-radiotherapy patients was dependent on the radiotherapy techniques; this may be related to the different radiation doses delivered to the parotid glands.In another study, we compared the parotid gland volume of a group of NPC patients before and 2–3 years after radiotherapy using CT [3]. The results of the study showed that the parotid gland volume decreased after radiotherapy and the degree of parotid volume shrinkage was dose-dependent [3].The assessment of salivary glands after radiotherapy is important [4]. Radiologists and sonographers should be aware of the dose- and radiotherapy technique-dependent variations of parotid glands when examining patients with previous head and neck radiotherapy.References1 Gossner J . Post-radiogenic density changes on CT of the salivary gland are time- dependent. Br J Radiol 2011;84 Link ISI, Google Scholar2 Cheng SCH , Ying MTC , Kwong DLW , Wu VWC . Sonographic appearance of parotid glands in patients treated with intensity-modulated radiotherapy or conventional radiotherapy for nasopharyngeal carcinoma. Ultrasound Med Biol 2011;37:220–30. Crossref Medline ISI, Google Scholar3 Wu VWC , Ying MTC , Kwong DLW . Evaluation of radiation-induced changes to parotid glands following conventional radiotherapy in patients with nasopharyngeal carcinoma. Br J Radiol 2011;84:843–849. Link ISI, Google Scholar4 Cheng SCH , Wu VWC , Kwong DLW , Ying MTC . Assessment of post-radiotherapy salivary glands. Br J Radiol 2011;84:393–402. Link ISI, Google Scholar Previous article Next article FiguresReferencesRelatedDetailsCited byA Review on the Assessment of Radiation Induced Salivary Gland Damage After Radiotherapy17 October 2019 | Frontiers in Oncology, Vol. 9 Volume 84, Issue 1008December 2011Pages: 1061-e245 2011 The British Institute of Radiology History ReceivedJune 28,2011AcceptedJuly 05,2011Published onlineFebruary 13,2014 Metrics Download PDF

High-efficiency immunomagnetic isolation of solid tissue-originated integrin-expressing adult stem cells

Isolation of highly pure specific cell types is crucial for successful adult stem cell-based therapy. As the number of such cells in adult tissue is low, an extremely efficient method is needed for their isolation. Here, we describe cell-separation methodologies based on magnetic-affinity cell sorting (MACS) MicroBeads with monoclonal antibodies against specific membrane proteins conjugated to superparamagnetic particles. Cells labeled with MACS MicroBeads are retained in a magnetic field within a MACS column placed in a MACS separator, allowing fast and efficient separation. Both positively labeled and non-labeled fractions can be used directly for downstream applications as the separated cell fractions remain viable with no functional impairment. As immunomagnetic separation depends on the interaction between a cell’s membrane and the magnetically labeled antibody, separation of specific cells originating from solid tissues is more complex and demands a cell-dissociating pretreatment. In this paper, we detail the use of immunomagnetic separation for the purpose of regenerating damaged salivary gland (SG) function in animal and human models of irradiated head and neck cancer. Each year 500,000 new cases of head and neck cancer occur worldwide. Most of these patients lose SG function following irradiation therapy. SGs contain integrin α6β1-expressing epithelial stem cells. We hypothesized that these cells can be isolated, multiplied in culture and auto-implanted into the irradiated SGs to regenerate damaged SG function.

Regeneration of radiation damaged salivary glands with adipose-derived stromal cells

Radiotherapy is one of the most effective treatments for head and neck cancer. However, the development of dry mouth syndrome is an unavoidable side effect because, in addition to the tumor, the normal salivary glands are included in the irradiation field. Previously, we investigated the protective efficacy of basic fibroblast growth factor (bFGF) in radiation-damaged salivary glands. In this study, we investigated the efficacy of adipose-derived stromal cell (ADSC) transplantation for the regeneration of radiation damaged salivary glands. Prospective animal experiment with control. ADSCs (500,000 cells isolated from green fluorescent protein mice) were transplanted into submandibular glands of C57BL/6 mice 10 weeks after 10 Gy irradiation (ADSC group). Phosphate-buffered saline was administered to mice as a control (sham group). Submandibular gland morphology and saliva flow rate were assessed just prior to transplantation and at 5 and 10 weeks posttransplantation. Quantitative RT-PCR was performed to examine the response of irradiated submandibular glands to ADSC transplantation. Saliva flow rate in the ADSC group was improved compared to the sham group. Although acinar cell damage was detected in both groups, the proliferation of blood vessels and other paracrine effects were observed only in the ADSC group. Additionally, the differentiation of ADSCs into blood endothelial cells and ductal cells was also observed. Our study indicates that ADSCs have the potential to restore salivary gland function after irradiation. The restoration of blood flow within submandibular gland tissue may explain the beneficial effects of ADSCs.

O14. Radioprotective effect of local delivery of bFGF against radiation-induced salivary gland damage

O14. Radioprotective effect of local delivery of bFGF against radiation-induced salivary gland damage

DNA damage in salivary gland tissue in patients with chronic kidney disease, measured by the comet assay

The aim of this observational study was to investigate the relationship between DNA damage in minor accessory salivary glands, hyposalivation, and inflammation in patients with chronic kidney disease (CKD). DNA strand breaks and oxidative DNA lesions in salivary glands, inflammatory markers, and uremic state were measured in 79 patients with CKD and matched controls. CKD patients not yet on dialysis had significantly more, and dialysis patients significantly less, DNA strand breaks in salivary tissue compared with controls. All measured inflammatory markers were higher in patients with CKD compared with controls. Salivary secretion rates were significantly lower in dialysis patients compared with controls. A high level of salivary secretion rate at rest significantly predicted a high level of DNA strand breaks in patients with CKD. Dialysis patients had fewer DNA strand breaks in minor accessory salivary glands than controls, suggesting that peripheral tissue is differently affected by CKD than leukocytes.

The value of magnetic resonance sialography and magnetic resonance imaging versus conventional sialography of the parotid gland in the diagnosis and staging of Sjögren’s syndrome

IntroductionThe conventional sialography (CS) and minor salivary gland biopsy have been considered the cornerstones of the diagnosis of Sjögren’s syndrome (SS). However, they are invasive and with risk of complications to the patient. Magnetic resonance imaging (MRI) has been widely replacing conventional invasive examinations. They provide insufficient data for diagnosing and staging SS, because while they address the detection and diagnosis of parenchymal salivary gland disease they do not assess duct abnormalities. The introduction of magnetic resonance sialography (MRS) protocol was the first step towards non-ionizing non-invasive technique enables a more accurate assessment of the duct system. Moreover, it is postulated that the combined use of MRI and MRS is useful for the assessment of damaged salivary glands in SS. Aim of workThis preliminary study aimed to assess the role and efficacy of MRS and MRI in imaging the parotid gland in SS patients’ and to compare their results with that of CS in the diagnosis and staging of SS. Patients and methodsThe parotid gland was examined by MRS, MRI and CS in 15 SS patients. Scoring system for overall branching pattern, ductal system staging, sialectasis for both CS and MRS was used. MRI scoring system for glandular parenchymal pattern, size and contour and lymph node was used. ResultsThis revealed non-significant difference between CS and MRS findings in the diagnosis and staging of SS. Furthermore, no statistically significant correlation was found between the clinical and SS stage in both CS and MRS. On the other hand, a statistically significant positive correlation was found between the clinical findings and the MRI parenchymal stages. Moreover, MRS showed higher sensitivity and diagnostic accuracy values than CS. Combining the MRS and MRI abnormalities, 100% sensitivity diagnostic accuracy values were achieved in the diagnosis and staging of SS. The inter-observer agreement was higher in MRS than in CS and was perfect in MRI. ConclusionIn this preliminary study, MRS showed a higher sensitivity and accuracy in diagnosing and staging SS and may safely and securely replace CS. MRI and MRS give information on different aspects of glandular and duct pathology; therefore, both should be performed when examining the parotid glands in SS patients.

Impact of radiotherapy dose on dentition breakdown in head and neck cancer patients

PurposeTo evaluate the severity of post-radiation dental lesions and possible correlation with radiation dose to the teeth in patients treated for head and neck cancers. Methods and MaterialsData from 93 head and neck radiotherapy patients treated between 1997 and 2008 were analyzed retrospectively. The main effect, radiation dose to the individual teeth, was evaluated with covariates of elapsed time after radiation, xerostomia, topical fluoride use, and oral hygiene status included. Patients’ radiotherapy plans were used to calculate cumulative exposure for each tooth. Patients’ teeth were evaluated using a validated index and then categorized as having none-slight or moderate-severe post-radiation damage. ResultsPatients (31 females, 62 males) ranged in age from 18-82 years (mean 57). The number of teeth-patient ranged from 3-30 (mean 20) with a total of 1873 teeth evaluated. Overall, 51% of teeth had moderate-severe damage, with the remaining having little or none. Using odds ratios and 95% confidence intervals, the odds for moderate-severe damage were 2-3 times greater for teeth exposed to between 30 and 60 Gy as compared to no radiation. However, for teeth exposed to ≥ 60 Gy as compared to no radiation the odds of moderate-severe tooth damage was greater by a magnitude of 10 times. ConclusionsThe results indicate that there is minimal tooth damage below 30 Gy (salivary gland threshold), a greater than 1:1 increased dose-response between 30 and 60 Gy likely related to salivary gland damage, and a critical threshold of ≥ 60 Gy, which may be linked to direct effects of radiation on tooth structure. These findings suggest that care should be taken during the treatment planning process to limit tooth dose, and when clinically possible to limit tooth dose to less than 60 Gy.

Does hyperbaric oxygen treatment have the potential to increase salivary flow rate and reduce xerostomia in previously irradiated head and neck cancer patients? A pilot study

Irradiated head and neck cancer survivors treated in the Hyperbaric Oxygen (HBO) Unit, Copenhagen University Hospital, spontaneously reported improvement of radiation-induced dry mouth feeling. The aim of this pilot study was to evaluate salivary flow rate and xerostomia before and after HBO in irradiated head and neck cancer patients. Eighty patients eligible for HBO treatment on the indication of prevention/treatment of osteoradionecrosis or soft tissue radiation injury were consecutively sampled, of whom 45 had hyposalivation (i.e. unstimulated whole saliva (UWS) flow rate <0.1ml/min), and 69 complained of xerostomia. UWS and stimulated whole saliva (SWS) were collected prior to and after 30 sessions of hyperbaric oxygen treatment over 6weeks. Xerostomia was assessed using the visual analogue scale (VAS). Each HBO session involved compression to 243kPa (2.4 ATA) for 90min while breathing 100% oxygen from a facemask or hood. There was a significant decrease in xerostomia (p<0.001) and slight increase in UWS (p<0.001) and SWS (p<0.001) flow rate, from before HBO as compared to after. Twenty-five of 45 patients with hyposalivation achieved an increased UWS flow rate after HBO. In 12 of these, the flow rates increased to levels not associated with hyposalivation. Patient-assessed improvement of xerostomia and slightly increased UWS and SWS secretion after HBO treatment suggest that HBO may have a beneficial effect on radiation-induced salivary gland damage.

Alterations in type I hemidesmosome components suggestive of epigenetic control in the salivary glands of patients with Sjögren's syndrome

AbstractObjectiveAcinar cells in the salivary glands of patients with Sjögren's syndrome (SS) display severe alterations in anchorage to the basal lamina. Bioinformatics analysis of the BP230 gene sequence has revealed the presence of CpG islands that might be involved in epigenetic control of gene expression, and methylation of the BP230 promotor region may be implicated as an epigenetic control mechanism in salivary gland damage. Thus, the present study was undertaken to evaluate the protein BP230, as well as proteins BP180, α6β4 integrin, and cytokeratin‐18, for their expression levels, localization, and ability to form hemidesmosome adhesion complexes.MethodsEighteen patients with primary SS and 14 healthy control subjects were studied. Levels of messenger RNA (mRNA) and protein were measured by reverse transcription–polymerase chain reaction and Western blotting, respectively. BP230 methylation was determined by methylation‐sensitive polymerase chain reaction. Protein complexes were analyzed by immunoprecipitation and assessed for localization by immunofluorescence.ResultsIn patients with SS as compared with controls, BP230 mRNA levels were decreased while protein levels were increased, and the gene promotor region was hypermethylated. Augmented proteolysis of BP180 was detected, since levels of linear IgA disease fragment 1 were increased. The complex‐forming ability of BP230, BP180, α6β4 integrin, and cytokeratin‐18 was maintained in patients with SS, in contrast to that in controls. BP230 and BP180 colocalized at the basal membrane of acinar cells, and cleavage of BP180 coincided with a loss of colocalization.ConclusionThe decrease in BP230 mRNA levels may be explained by gene hypermethylation. We postulate that local epigenetic modifications of BP230 are produced in response to factors present in the damaged salivary glands of patients with SS. Additionally, the paradoxical increase in BP230 protein levels and the formation of both normal and altered adhesion complexes may help avoid cell death induced by the loss of anchorage.

Human Mesenchymal Stem Cells Cultured with Salivary Gland Biopsies Adopt an Epithelial Phenotype

Sjogren's syndrome and radiotherapy for head and neck cancer result in severe xerostomia and irreversible salivary gland damage for which no effective treatment is currently available. Cell culture methods of primary human salivary gland epithelial cells (huSGs) are slow and cannot provide a sufficient number of cells. In addition, the majority of cultured huSGs are of a ductal phenotype and thus not fluid/saliva secretory cells. Some reports indicated that mesenchymal stem cells (MSCs) possessed the potential to differentiate into epithelial cells. To test this hypothesis with huSGs, a coculture system containing 2 chambers separated by a polyester membrane was used to study the capacity of human MSCs to adopt an epithelial phenotype when cocultured with human salivary gland biopsies. Results were that 20%-40% of cocultured MSCs expressed tight junction proteins [claudin-1 (CLDN-1), -2, -3, and -4; occludin; junctional adhesion molecule-A; and zonula occludens-1] as well as other epithelial markers [aquaporin-5, α-amylase (α-AMY), and E-cadherin], and generated a higher transepithelial electrical resistance. Electron microscopy demonstrated that these MSCs had comparable cellular structures to huSGs, such as tight junction structures and numerous secretory granules. Quantitative real time (RT)-polymerase chain reaction revealed an upregulation of several salivary genes (aquaporin-5, AMY, and CLDN-2). Moreover, the amounts of α-AMY detected in cocultured MSCs were comparable to those detected in huSGs control cultures. These data suggest that cocultured MSCs can demonstrate a temporary change into a salivary gland acinar phenotype.

Proefschriften 25 jaar na dato 23. Ontwikkelingen in preventie en behandeling van xerostomie

Twenty-five years ago, the treatment of xerostomia was predominantly symptomatic. At that time, the treatment possibilities were mainly sialogogues, mouthrinses and saliva substitutes. Since then, there have been few changes in the symptomatic treatment of xerostomia. Methods to prevent the development of xerostomia or to reduce its severity were then in their infancy and methods aiming to regenerate a damaged salivary gland did not exist. During the last 2 decades, however, great changes have taken place. New radiation techniques reducing the cumulative dose on salivary glands have been introduced. At the moment techniques are being developed to regenerate the secretory potential of a salivary gland damaged by radiotherapy. In addition, biologicals have recently been introduced which make it possible to intervene in the process of disease associated with Sjögren's syndrome, by means of which here, too, a degree of regeneration of function can be achieved.

Stem cells and the repair of radiation‐induced salivary gland damage

Hyposalivation underlying xerostomia after radiotherapy is still a major problem in the treatment of head and neck cancer. Stem cell therapy may provide a means to reduce radiation-induced hyposalivation and improve the quality of life of patients. This review discusses the current status in salivary gland stem cell research with respect to their potential to attenuate salivary gland dysfunction. Knowledge on the embryonic development, homeostasis and regeneration after atrophy of the salivary glands has provided important knowledge on the location of the salivary gland as well as on the factors that influence proliferation and differentiation. This knowledge has helped to locate, isolate and characterize cell populations that contain the salivary gland stem cell, although the exact tissue stem cell is still unidentified. The role that stem/progenitor cells play in the response to radiation and the factors that can influence stem/progenitor induced proliferation and differentiation are discussed. Finally, the mobilization and transplantation of stem cells and supportive cells and their potential to attenuate radiation-induced salivary gland damage are discussed. Based on the major advances made in the field of stem cell research, stem cell-based therapy has great potential to allow prevention or treatment of radiation-induced hyposalivation.