Salivary Gland Damage Research Articles

Indomethacin Treatment Post-irradiation Improves Mouse Parotid Salivary Gland Function via Modulation of Prostaglandin E2 Signaling

Annually, >600,000 new cases of head and neck cancer (HNC) are diagnosed worldwide with primary treatment being surgery and radiotherapy. During ionizing radiation (IR) treatment of HNC, healthy salivary glands are collaterally damaged, leading to loss of function that severely diminishes the quality of life for patients due to increased health complications, including oral infections and sores, cavities, and malnutrition, among others. Therapies for salivary hypofunction are ineffective and largely palliative, indicating a need for further research to uncover effective approaches to prevent or restore loss of salivary gland function following radiotherapy. Previous work in our lab implicated prostaglandin E2 (PGE2) as an inflammatory mediator whose release from radiation-exposed cells promotes salivary gland damage and loss of function. Deletion of the P2X7 purinergic receptor for extracellular ATP reduces PGE2 secretion in irradiated primary parotid gland cells, and salivary gland function is enhanced in irradiated P2X7R–/– mice compared to wild-type mice. However, the role of PGE2 signaling in irradiated salivary glands is unclear and understanding the mechanism of PGE2 action is a goal of this study. Results show that treatment of irradiated mice with the non-steroidal anti-inflammatory drug (NSAID) indomethacin, which reduces PGE2 production via inhibition of cyclooxygenase-1 (COX-1), improves salivary gland function compared to irradiated vehicle-treated mice. To define the signaling pathway whereby PGE2 induces salivary gland dysfunction, primary parotid gland cells treated with PGE2 have increased c-Jun N-terminal Kinase (JNK) activation and cell proliferation and reduced amylase levels and store-operated calcium entry (SOCE). The in vivo effects of blocking PGE2 production were also examined and irradiated mice receiving indomethacin injections have reduced JNK activity at 8 days post-irradiation and reduced proliferation and increased amylase levels at day 30, as compared to irradiated mice without indomethacin. Combined, these data suggest a mechanism whereby irradiation-induced PGE2 signaling to JNK blocks critical steps in saliva secretion manifested by a decrease in the quality (diminished amylase) and quantity (loss of calcium channel activity) of saliva, that can be restored with indomethacin. These findings encourage further attempts evaluating indomethacin as a viable therapeutic option to prevent damage to salivary glands caused by irradiation of HNC in humans.

Effects of oligonol on the submandibular gland in ovariectomized rats

The aim of this study was to observe the effects of oligonol on submandibular gland dysfunction in ovariectomized rats. We randomly divided female Sprague-Dawley rats into sham-operated, ovariectomized, and oligonol-treated ovariectomized groups. Oligonol was intraperitoneally administered at 30 mg/kg daily for six weeks. Lipogenesis increased after the ovariectomy while fatty acid oxidation increased and intracellular triglyceride levels decreased in response to oligonol treatment. Submandibular gland fibrosis characterized by collagen type I accumulation was observed in the ovariectomized group. However, oligonol markedly reduced fibrosis to a level comparable to that observed in the sham group. Aquaporin 1 and glucose transporter 4 were downregulated in the ovariectomized group. Nevertheless, both factors were significantly upregulated by oligonol treatment. However, aquaporin 5 was significantly downregulated in the oligonol treatment group. Our findings indicate that oligonol protects against damage in postmenopausal rat salivary glands.

Mapping Salivary Proteases in Sjögren's Syndrome Patients Reveals Overexpression of Dipeptidyl Peptidase-4/CD26.

Sjögren’s Syndrome (SS) is an autoimmune exocrinopathy characterized by the progressive damage of salivary and lacrimal glands associated with lymphocytic infiltration. Identifying new non-invasive biomarkers for SS diagnosis remains a challenge, and alterations in saliva composition reported in patients turn this fluid into a source of potential biomarkers. Among these, proteases are promising candidates since they are involved in several key physio-pathological processes. This study evaluated differentially expressed proteases in SS individuals’ saliva using synthetic fluorogenic substrates, zymography, ELISA, and proteomic approaches. Here we reported, for the first time, increased activity of the serine protease dipeptidyl peptidase-4/CD26 (DPP4/CD26) in pSS saliva, the expression level of which was corroborated by ELISA assay. Gelatin zymograms showed that metalloproteinase proteolytic band profiles differed significantly in intensity between control and SS groups. Focusing on matrix metalloproteinase-9 (MMP9) expression, an increased tendency in pSS saliva (p = 0.0527) was observed compared to the control group. Samples of control, pSS, and sSS were analyzed by mass spectrometry to reveal a general panorama of proteases in saliva. Forty-eight protein groups of proteases were identified, among which were the serine proteases cathepsin G (CTSG), neutrophil elastase (ELANE), myeloblastin (PRTN3), MMP9 and several protease inhibitors. This work paves the way for proteases to be explored in the future as biomarkers, emphasizing DPP4 by its association in several autoimmune and inflammatory diseases. Besides its proteolytic role, DPP4/CD26 acts as a cell surface receptor, signal transduction mediator, adhesion and costimulatory protein involved in T lymphocytes activation.

Progressive changes in the major salivary gland after radioiodine therapy for differentiated thyroid cancer: a single-center retrospective ultrasound cohort study

This study aimed to determine the prevalence of radioiodine-induced salivary gland damage by evaluating progressive changes in salivary glands using ultrasound. Four hundred forty-six patients with differentiated thyroid carcinoma who underwent total or near-total thyroidectomy and postoperative radioiodine therapy were retrospectively reviewed. From the first to the fifth follow-up visits, the positive rate of major salivary gland changes on ultrasound gradually increased from 2.0% to 33.0% (P<0.001) and possibly stabilized at the fifth visit (approximately 36 months). The first positive result was detected at an average of 20.78±8.72 months. Only 21 of the 161 positive cases eventually achieved negative ultrasound results (Fisher's test, P<0.001), and the 21 cases simply showed a coarse echotexure. In conclusion, ultrasound changes appeared late, and most of these changes were not reversed.

Protective effects of miR-155-5p silencing on IFN-γ-induced apoptosis and inflammation in salivary gland epithelial cells.

Previous studies have demonstrated that microRNAs (miRNAs/miRs) serve a vital role in the pathogenesis of Sjögren's syndrome (SS). The present study aimed to investigate the role of miR-155-5p in SS and determine its underlying molecular mechanism. An inflammatory lesion model was established by stimulating salivary gland epithelial cells (SGECs) with interferon-γ (IFN-γ). The apoptosis of SGECs was measured by using flow cytometry. Levels of proinflammatory factors were detected by reverse transcription-quantitative PCR and ELISA, respectively. Immunofluorescence was used for p65 staining. Dual-luciferase reporter assay was performed to verify the interaction between miR-155-5p and arrestin β2 (ARRB2). The protein levels in the NF-κB signaling pathway were assessed by western blotting. The results of the present study demonstrated that treatment with IFN-γ increased miR-155-5p expression, in addition to inducing apoptosis and inflammation in SGECs. Furthermore, overexpression of miR-155-5p promoted IFN-γ-induced apoptosis and inflammation in SGECs. Overexpression of miR-155-5p also increased Bax protein expression, enzyme activities of caspase 3 and caspase 9, release of inflammatory cytokines interleukin-6 and tumor necrosis factor-α, and decreased Bcl-2 protein expression in IFN-γ-treated SGECs. By contrast, all of the effects aforementioned were reversed following miR-155-5p knockdown. These results demonstrated that miR-155-5p activated the NF-κB signaling pathway, where treatment with the NF-κB inhibitor, pyrrolidine dithiocarbamate, reversed the effects of miR-155-5p overexpression on the inflammatory factors in IFN-γ-induced SGECs. miR-155-5p was demonstrated to target ARRB2 and negatively regulated its expression levels, such that overexpression of ARRB2 reversed the effects of miR-155-5p overexpression on the inflammatory response, apoptosis and the NF-κB signaling pathway in IFN-γ-treated SGECs. Collectively, results from the present study suggest that miR-155-5p may activate the NF-κB signaling pathway by negatively regulating ARRB2 to promote salivary gland damage during SS pathogenesis. This suggests that miR-155-5p may serve to be a potential target for the treatment of SS.

Effect of Bone Marrow Derived-Mesenchymal Stem Cells on Submandibular Salivary Glands of Carbimazole Induced Hypothyroidism in Albino Rats

Purpose: This study was aimed to estimate the effect of bone marrow derived mesenchymal stem cells (BM-MSCs) on the submandibular salivary gland of induced hypothyroidism in rats. Material and Methods: Thirty adult male albino rats weighing between 200-250 grams were used in the present study. The animals were divided into three equal groups: Group I (control group), Group II (carbimazole induced hypothyroidism group): Rats received a daily dose of carbimazole (5mg/250g/day) for 5 weeks, Group III (BM-MSCs treated group): Hypothyroidism was induced similar to group II, then rats were injected with 1x 107 BM-MSCs cells. All Rats were euthanized after 8 weeks (5 weeks of hypothyroidism induction + 3 weeks of stem cells injection). Results: group (II) showed excessive destruction and degenerative changes of the acini and ducts in comparison to group (I), while group (III) revealed marked improvement of the parenchymal elements after BM-MSCs injection. Conclusions: This study supposes that BM-MSCs improve salivary glands damage following induction of hypothyroidism. Therefore, BM-MSCs can be applied as cell-based therapy for restoration of hypothyroid-induced salivary hypofunction.

Comparative characteristics of the clinical and laboratory features of the primary Sjogren’s syndrome associated with anticentromere antibodies and the “classic” subtype of the disease

Objective: to compare clinical and laboratory manifestations in 2 groups of patients with primary Sjogren’s syndrome (pSS): with and without anticentromere antibodies (ACA); compare the incidence, clinical and laboratory characteristics of lymphomas in these two groups.Materials and methods. We examined 119 patients with ACA-positive pSS (pSS-ACA+). pSS was diagnosed based on Russian 2001 criteria, systemic sclerosis (SSc) – criteria ACR/EULAR 2013. To diagnose liver diseases, the level of transaminases, alkaline phosphatase and antimitochondrial antibodies (AMA) was determined, as well as liver biopsy. The diagnosis of primary biliary cholangitis (PBC) was established according to the recommendations of the American Association for the Study of Liver Diseases, the Russian Gastroenterological Association and the Russian Society for the Study of the Liver. Lymphomas were diagnosed according to histological, immunohistochemical and molecular studies of affected organs biopsies, according to the classification of the World Health Organization. A combination of pSS and SSc was diagnosed in 37 patients, and they were excluded from further analysis. We compared clinical and laboratory features in patients with pSS-ACA+ (n=82) and ACA-negative pSS (pSS-ACA–, n=64) and characterized lymphomas in the pSS-ACA+ (n = 14) and pSS-ACA– (n=10) groups.Results and discussion. In patients with pSS-ACA+, a later age of disease onset was revealed, the duration of the disease before lymphoma development did not differ. In patients with pSS-ACA+, we found a lower frequency of rheumatoid factor (RF), antibodies to Ro (anti-Ro) and La (anti-La), decreased C3-complement, hypergammaglobulinemia, increased IgG concentration, CRP, increased ESR, leukopenia and anemia. 51.2% of patients with pSS-ACA+ were seronegative for anti-Ro, anti-La and RF. Patients with pSS-ACA+ had a higher frequency of AMA and elevated IgM. The incidence of cryoglobulinemia and paraproteinemia did not differ. The frequency of recurrent parotitis in pSS-ACA+ was significantly lower, there were no differences in the frequency and severity of other signs of salivary and lacrimal gland damage. PBC and epitheliitis of the biliary ducts in patients with pSS-ACA+ were detected significantly more often. Damage to the peripheral nervous system, lungs, hypergammaglobulinemic purpura, arthralgia and autoimmune thyroiditis were significantly more often detected in the group of patients with pSS-ACA–. In the pSS-ACA+ group, Raynaud’s phenomenon was significantly more frequent, mainly with scleroderma-type capillaroscopic abnormalities. There was no difference in the frequency of other signs characteristic of SSc. MALT lymphomas were diagnosed in the study groups with the same frequency. Patients with lymphomas in the pSS-ACA+ group were characterized by significantly higher laboratory activity. All patients with lymphomas in both groups showed persistent parotid salivary gland enlargement. Lymphomas in both groups developed in patients with late stage salivary and lacrimal gland damage, systemic manifestations of pSS in both groups were rare.Conclusion. pSS-ACA+ is an independent subtype of pSS, which has a number of significant clinical and laboratory differences from the “classic” variant of the disease. ACA in pSS are associated with a low frequency of anti-Ro, anti-La, and RF, as well as an increased risk of PBC and limited SSc. MALT lymphomas in the pSS-ACA+ and pSS-ACA– groups developed with the same frequency and were associated with the progression of glandular damage, regardless of the presence of systemic manifestations.

Application of regenerative medicine to salivary gland hypofunction.

Dry mouth results from hypofunction of the salivary glands due to Sjögren's syndrome (SS), various medications, and radiation therapy for head and neck cancer. In severe cases of salivary gland hypofunction, sialagogues are not always effective due to the loss of salivary parenchyma. Therefore, regenerative medicine using stem cell therapy is a promising treatment for severe cases. Stem cells are classified into three groups: tissue stem cells, embryonic stem cells, and induced pluripotent stem cells. Tissue stem cells, such as hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs) and salivary stem/progenitor cells, could rescue irradiation-induced salivary gland hypofunction. Both HSCs and MSCs can rescue salivary gland hypofunction through soluble factors in a paracrine manner, while salivary stem/progenitor cells can reconstitute the damaged salivary glands. In fact, we clarified that CD133-positive cells in mouse submandibular glands showed stem cell features, which reconstituted the damaged salivary glands. Furthermore, we focused on the challenge of producing functional salivary glands that are three-dimensionally induced from mouse ES cells.

Evaluation Of Curcumin And Chitosan Protective Effect On Submandibular Salivary Gland Toxicity Induced By Monosodium Glutamate In Male Albino Rats

ABSTRACT Monosodium glutamate is a well-known food flavor additives that is widely used all over the world but its chronic intake leads to many reported side effects. Aim of the study: The goal of this study was to evaluate the prophylactic role of chitosan and curcumine extract, as a well-known antioxidant, against the submandibular salivary gland (SMG) damage induced by chronic intake of monosodium glutamate (MSG). Material and methods: 36 adult male Albino rats were randomly divided into 4 groups; Group 1 (control) group, group2 (MSG group): rats received a daily dose of MSG only by oral gavage, group 3 ( MSG + Chitosan treated group): rats received a daily dose of MSG + chitosan and finally group 4 ( MSG + curcumin treated group): rats received a daily dose of MSG + curcumin. After 6 weeks, the submandibular salivary glands were excised and processed for histological and caspase 3 immunohistochemical examination. Results: histological examination by H&E stain of group 3 and 4 revealed improvement of secretory portion architecture in addition to decreased vaculation and pleomorphism than group 2. There were a high statistical significant difference, of caspase 3 immuno-expression, between the treated chitosan and curcumin groups (group3 and 4) and MSG group (group 2) as p values were 0.005 and 0.017 respectively. Conclusion: administration of chitosan or curcumin has a protective effect on SMG toxicity induced by chronic intake of MSG.

Protective effect of nano vitamin D against fatty degeneration in submandibular and sublingual salivary glands: A histological and ultrastructural study

BackgroundPoor nutritional habits and a low level of physical activity are associated with obesity, leading to increased caloric and fat intakes. A high-fat diet can significantly impact oral health through the accumulation of lipids in the salivary glands, which ultimately affect salivary gland function. Recently, an increasing number of supplement nano-formulations, such as nano vitamin D, have become available. However, only few studies have explored the effects of nano vitamin D on the maintenance of oral health. ObjectiveThis study aimed to compare the histological effects of nano vitamin D to those of regular vitamin D on fatty degeneration in submandibular and sublingual salivary glands using a rat model. MethodsTwenty-four adult male albino Sprague–Dawley rats were divided into the following groups: untreated group, high-fat diet group, high-fat diet and regular vitamin D group, and high-fat diet and nano vitamin group.Thereafter, samples of the submandibular and sublingual salivary glands were dissected for histological and electron microscopic studies. Morphometric digital image analysis was used to quantitatively measure the changes in the size and number of acini and secretory granules. ResultsRegular vitamin D had a partial protective effect. However, vitamin D could fully restore cellular structures to their normal state, thereby protecting against fatty degeneration of the salivary tissue and immune cell infiltration, particularly in the submandibular serous tissue. Nano vitamin D was more efficacious than regular vitamin D at restoring the number and size of submandibular serous secretory granules. ConclusionEmploying nano vitamin D as a supplement to high-fat diets could protect against high-fat diet-induced salivary gland damage in rats.

THE EFFECT OF BONE MARROW DERIVED MESENCHYMAL STEM CELLS ON THE ULTRASTRUCTURE OF SUBMANDIBULAR SALIVARY GLAND OF INDUCED HYPOTHYROIDISM IN RATS (ELECTRON MICROSCOPIC STUDY)

Background: Hypothyroidism is a clinical disorder that results from insufficient production of thyroid hormones leading to a total decrease of metabolic demands of the body and causing serious abnormalities. Hypothyroidism is known to affect salivary glands causing deleterious changes including apoptosis and numerous cytoplasmic vacuolation. Mesenchymal stem cells (MSCs) have high capability of self-renewal. Thus, have enormous therapeutic potential for tissue repair. Objective: The study aimed to assess the influence of bone marrow derived mesenchymal stem cells (BM-MSCs) on the histological ultrastructure of submandibular salivary gland of carbimazole-induced hypothyroidism in rats. Method: Twenty one adult male albino rats were divided into three groups (seven rats each). Group I: Is considered as control group. Group II: (Carbimazole induced hypothyroidism group): animals were given a single daily oral dose of carbimazole (5mg/250g/day) dissolved in 3 ml of distilled water delivered by intragastric tube for five weeks, to induce hypothyroidism. Group III: (BM-MSCs treated group): hypothyroidism was induced similar to group II. Then rats were injected at the lateral tail vein with 1x 107 BM-MSCs cells in 0.2ml phosphate buffer saline immediately following induction of hypothyroidism. All rats were euthanized after 8 weeks (5 weeks of hypothyroidism induction + 3 weeks of stem cells injection). Submandibular salivary glands were prepared for transmission electron microscopic examination (TEM). Results: Ultrastructural results of group II revealed massive degenerative changes within the acinar and ductal cells’ nuclei and organelles, together with disruption of their intercellular junctions. Marked improvement of parenchymal cells’ architecture was detected with BM-MSCs administration in group III. Conclusion: BM-MSCs have the potentiality to repair salivary glands damage following induction of hypothyroidism.

Integration of metabolomics and transcriptomics reveals convergent pathways driving radiation-induced salivary gland dysfunction.

Radiation therapy for head and neck cancer causes damage to the surrounding salivary glands, resulting in salivary gland hypofunction and xerostomia. Current treatments do not provide lasting restoration of salivary gland function following radiation; therefore, a new mechanistic understanding of the radiation-induced damage response is necessary for identifying therapeutic targets. The purpose of the present study was to investigate the metabolic phenotype of radiation-induced damage in parotid salivary glands by integrating transcriptomic and metabolomic data. Integrated data were then analyzed to identify significant gene-metabolite interactions. Mice received a single 5 Gy dose of targeted head and neck radiation. Parotid tissue samples were collected 5 days following treatment for RNA sequencing and metabolomics analysis. Altered metabolites and transcripts significantly converged on a specific region in the metabolic reaction network. Both integrative pathway enrichment using rank-based statistics and network analysis highlighted significantly coordinated changes in glutathione metabolism, energy metabolism (TCA cycle and thermogenesis), peroxisomal lipid metabolism, and bile acid production with radiation. Integrated changes observed in energy metabolism suggest that radiation induces a mitochondrial dysfunction phenotype. These findings validated previous pathways involved in the radiation-damage response, such as altered energy metabolism, and identified robust signatures in salivary glands, such as reduced glutathione metabolism, that may be driving salivary gland dysfunction.

Olfactory ecto-mesenchymal stem cell-derived exosomes ameliorate murine Sj\xf6gren\u2019s syndrome by modulating the function of myeloid-derived suppressor cells

Sjögren’s syndrome (SS) is a systemic autoimmune disease characterized by progressive inflammation and tissue damage in salivary glands and lacrimal glands. Our previous studies showed that myeloid-derived suppressor cells (MDSCs) exhibited impaired immunosuppressive function during disease progression in patients with SS and mice with experimental Sjögren’s syndrome (ESS), but it remains unclear whether restoring the function of MDSCs can effectively ameliorate the development of ESS. In this study, we found that murine olfactory ecto-mesenchymal stem cell-derived exosomes (OE-MSC-Exos) significantly enhanced the suppressive function of MDSCs by upregulating arginase expression and increasing ROS and NO levels. Moreover, treatment with OE-MSC-Exos via intravenous injection markedly attenuated disease progression and restored MDSC function in ESS mice. Mechanistically, OE-MSC-Exo-secreted IL-6 activated the Jak2/Stat3 pathway in MDSCs. In addition, the abundant S100A4 in OE-MSC-Exos acted as a key factor in mediating the endogenous production of IL-6 by MDSCs via TLR4 signaling, indicating an autocrine pathway of MDSC functional modulation by IL-6. Taken together, our results demonstrated that OE-MSC-Exos possess therapeutic potential to attenuate ESS progression by enhancing the immunosuppressive function of MDSCs, possibly constituting a new strategy for the treatment of Sjögren’s syndrome and other autoimmune diseases.

Triptolide reduces salivary gland damage in a non-obese diabetic mice model of Sjögren's syndrome via JAK/STAT and NF-κB signaling pathways.

Triptolide (TP) has anti-inflammatory and immunosuppressive effects. However, the effect of triptolide on Sjögren's syndrome (SS) is rarely reported. In this paper, we studied the effects of triptolide on non-obese diabetes mice model of SS. In this study, salivary flow rate was measured every two weeks, and autoantibodies levels in the serum were detected. Salivary gland index and spleen index were detected, pathological changes of salivary gland were detected by hematoxylin-eosin staining, inflammatory factors were detected by enzyme linked immunosorbent assay, lymphocytes were detected by flow cytometry, proliferation of T cells and B cells were detected, and related proteins were detected by Western blot. Triptolide increased salivary flow rate and salivary gland index, and decreased spleen gland index. Moreover, triptolide reduced the infiltration of lymphocytes to salivary glands, decreased the level of autoantibodies in serum, and reduced the inflammatory factors in salivary glands and IFN-γ induced salivary gland epithelial cells. Further, triptolide inhibited activator of JAK/STAT pathway and NF-κB pathway. In conclusion, triptolide could inhibit the infiltration of lymphocytes and the expression of inflammatory factors through JAK/STAT pathway and NF-κB pathway. Thus, triptolide may be used as a potential drug to treat SS.

Radiation-Induced Salivary Gland Dysfunction: Mechanisms, Therapeutics and Future Directions.

Salivary glands sustain collateral damage following radiotherapy (RT) to treat cancers of the head and neck, leading to complications, including mucositis, xerostomia and hyposalivation. Despite salivary gland-sparing techniques and modified dosing strategies, long-term hypofunction remains a significant problem. Current therapeutic interventions provide temporary symptom relief, but do not address irreversible glandular damage. In this review, we summarize the current understanding of mechanisms involved in RT-induced hyposalivation and provide a framework for future mechanistic studies. One glaring gap in published studies investigating RT-induced mechanisms of salivary gland dysfunction concerns the effect of irradiation on adjacent non-irradiated tissue via paracrine, autocrine and direct cell–cell interactions, coined the bystander effect in other models of RT-induced damage. We hypothesize that purinergic receptor signaling involving P2 nucleotide receptors may play a key role in mediating the bystander effect. We also discuss promising new therapeutic approaches to prevent salivary gland damage due to RT.

Nerve growth factor protects salivary glands from irradiation-induced damage

AimsRadiotherapy has become a basic treatment modality for head and neck cancer. However, radiotherapy results in inevitable side effects, particularly radiation sialadenitis, that significantly impairs quality of life. A previous study indicated that nerve growth factor (NGF) has a radio-protective effect, but the mechanism was not determined in salivary glands. In this study, we explored the functional role and mechanism regarding how NGF protects salivary glands against IR-induced damage. Main methodsHuman salivary gland (HSG) cells and C57BL/6 mice were selected to establish an IR-induced salivary gland damage model in vitro and in vivo. Recombinant NGF protein and NGF siRNA and over-expression plasmids were applied to manipulate NGF expression in vitro. AAV-NGF was retrogradely perfused into the submandibular gland (SMG) through the SMG duct to manipulate NGF expression in vitro. Small-molecule inhibitors and siRNAs were applied to inhibit AKT and JNK. Western blotting, quantitative PCR, flow cytometry and histology assays were performed to analyse the functional role and mechanism of NGF. Key findingsOur study demonstrated that NGF expression was upregulated following radiotherapy both in human HSG cells and mouse SMG tissues. NGF could reduce IR-induced HSG cell apoptosis, and AAV-mediated gene therapy could restore the salivary flow rate and protect the salivary gland against IR-induced apoptosis in vivo. Mechanistically, NGF protects salivary glands from IR-induced apoptosis by de-phosphorylating JNK kinase rather than promoting AKT phosphorylation. SignificanceThe current study findings indicated that the modulation of the NGF pathway might prevent IR-induced salivary hypo-function.

Oral chronic graft-versus-host disease: What the general dental practitioner needs to know

BackgroundLong-term survivors of allogeneic hematopoietic cell transplantation will increasingly seek care from dental providers. MethodsThe authors highlight the importance of minimizing oral symptoms and complications associated with oral chronic graft-versus-host-disease (cGVHD). ResultsChronic GVHD is the result of an immune response of donor-derived cells against recipient tissues. Oral cGVHD can affect the mucosa and damage salivary glands and cause sclerotic changes. Symptoms include sensitivity and pain, dry mouth, taste changes, and limited mouth opening. Risk of developing caries and oral cancer is increased. Food intake, oral hygiene, and dental interventions can represent challenges. Oral cGVHD manifestations and dental interventions should be managed in close consultation with the medical team, as systemic treatment for cGVHD can have implications for dental management. ConclusionsGeneral dental practitioners can contribute substantially to alleviating oral cGVHD involvement and preventing additional oral health deterioration. Practical ImplicationsFrequent examinations, patient education, oral hygiene reinforcement, dry mouth management, caries prevention, and management of dental needs are indicated. In addition, oral physical therapy might be needed. Invasive dental interventions should be coordinated with the transplantation team. Screening for oral malignancies is important even years after resolution of GVHD symptoms. Management of the oral manifestations of cGVHD might require referral to an oral medicine professional.

Resident CD34-positive cells contribute to peri-endothelial cells and vascular morphogenesis in salivary gland after irradiation

Salivary gland (SG) hypofunction is a common post-radiotherapy complication. Besides the parenchymal damage after irradiation (IR), there are also effects on mesenchymal stem cells (MSCs) which were shown to contribute to regeneration and repair of damaged tissues by differentiating into stromal cell types or releasing vesicles and soluble factors supporting the healing processes. However, there are no adequate reports about their roles during SG damage and regeneration so far. Using an irradiated SG mouse model, we performed certain immunostainings on tissue sections of submandibular glands at different time points after IR. Immunostaining for CD31 revealed that already one day after IR, vascular impairment was induced at the level of capillaries. In addition, the expression of CD44—a marker of acinar cells—diminished gradually after IR and, by 20 weeks, almost disappeared. In contrast, the number of CD34-positive cells significantly increased 4 weeks after IR and some of the CD34-positive cells were found to reside within the adventitia of arteries and veins. Laser confocal microscopic analyses revealed an accumulation of CD34-positive cells within the area of damaged capillaries where they were in close contact to the CD31-positive endothelial cells. At 4 weeks after IR, a fraction of the CD34-positive cells underwent differentiation into α-SMA-positive cells, which suggests that they may contribute to regeneration of smooth muscle cells and/or pericytes covering the small vessels from the outside. In conclusion, SG-resident CD34-positive cells represent a population of progenitors that could contribute to new vessel formation and/or remodeling of the pre-existing vessels after IR and thus, might be an important player during SG tissue healing.

Cellular senescence contributes to radiation-induced hyposalivation by affecting the stem/progenitor cell niche

Radiotherapy for head and neck cancer is associated with impairment of salivary gland function and consequent xerostomia, which has a devastating effect on the quality of life of the patients. The mechanism of radiation-induced salivary gland damage is not completely understood. Cellular senescence is a permanent state of cell cycle arrest accompanied by a secretory phenotype which contributes to inflammation and tissue deterioration. Genotoxic stresses, including radiation-induced DNA damage, are known to induce a senescence response. Here, we show that radiation induces cellular senescence preferentially in the salivary gland stem/progenitor cell niche of mouse models and patients. Similarly, salivary gland-derived organoids show increased expression of senescence markers and pro-inflammatory senescence-associated secretory phenotype (SASP) factors after radiation exposure. Clearance of senescent cells by selective removal of p16Ink4a-positive cells by the drug ganciclovir or the senolytic drug ABT263 lead to increased stem cell self-renewal capacity as measured by organoid formation efficiency. Additionally, pharmacological treatment with ABT263 in mice irradiated to the salivary glands mitigates tissue degeneration, thus preserving salivation. Our data suggest that senescence in the salivary gland stem/progenitor cell niche contributes to radiation-induced hyposalivation. Pharmacological targeting of senescent cells may represent a therapeutic strategy to prevent radiotherapy-induced xerostomia.

ANALYSIS OF THE SALIVARY BIOCHEMISTRY OF TWO PATIENTS AFTER RADIOIODINE TREATMENT

Introduction: Salivary gland damage such as xerostomia and sialadenitis is one of the most frustrating complications after radioactive iodine (131I) therapy. Objective: This study aimed to evaluate salivary flow rate, pH, and salivary composition in patients exposed to 131I. Study Design: Two patients diagnosed with thyroid carcinoma had total thyroidectomy and 131I exposure in 2013 and 2015, respectively, and were evaluated by unstimulated whole saliva (UWS). After collection, the sample was weighted and the salivary flow rate was calculated. The pH analysis was determined by means of Digimed 2-D portable pH meter, total protein concentration in the saliva was assessed by the Lowry method, and amylase was determined by the Bellavia method. Results: The doses of radioiodine were 118.8 mCi for patient 1 and 152.3 mCi for patient 2. Regarding salivary pH, patient 1 was at 6.9 and patient 2 at 6.2. Total protein and alpha amylase was (15 000 ug/mL and 2870 mg/mL ) in patient 1 and (10.78 ug/mL and 2377 mg/mL) in patient 2. When comparing healthy saliva to the saliva after 131I, a significant decrease was noted in all parameters. Patients exposed to 131I present with salivary alterations even after years of treatment, which has an effect on their quality of life. Introduction: Salivary gland damage such as xerostomia and sialadenitis is one of the most frustrating complications after radioactive iodine (131I) therapy. Objective: This study aimed to evaluate salivary flow rate, pH, and salivary composition in patients exposed to 131I. Study Design: Two patients diagnosed with thyroid carcinoma had total thyroidectomy and 131I exposure in 2013 and 2015, respectively, and were evaluated by unstimulated whole saliva (UWS). After collection, the sample was weighted and the salivary flow rate was calculated. The pH analysis was determined by means of Digimed 2-D portable pH meter, total protein concentration in the saliva was assessed by the Lowry method, and amylase was determined by the Bellavia method. Results: The doses of radioiodine were 118.8 mCi for patient 1 and 152.3 mCi for patient 2. Regarding salivary pH, patient 1 was at 6.9 and patient 2 at 6.2. Total protein and alpha amylase was (15 000 ug/mL and 2870 mg/mL ) in patient 1 and (10.78 ug/mL and 2377 mg/mL) in patient 2. When comparing healthy saliva to the saliva after 131I, a significant decrease was noted in all parameters. Patients exposed to 131I present with salivary alterations even after years of treatment, which has an effect on their quality of life.