F-actin/DRP1 axis-mediated mitochondrial fission promotes mitophagy in diabetic submandibular glands

BACKGROUND

Diabetes is accompanied by a high prevalence of hyposalivation, causing severe damage to oral and systemic health. Mitochondrial dynamics play important roles in the pathogenesis of various diabetic complications; however, little is known about their roles in diabetic hyposalivation.

MATERIALS AND METHODS

A diabetic mouse model and a high glucose (HG)-induced diabetic submandibular gland (SMG) cell model were employed.

RESULTS

More mitochondria surrounded by autophagosomes and higher expression of mitophagy-related proteins were detected in the SMGs of diabetic mice and HG-treated SMG cells. In diabetic SMGs, dynamin-related protein 1 (DRP1) was upregulated, whereas mitofusin-2 was downregulated both in vivo and in vitro. Shortened mitochondria and impaired mitochondrial functions were observed in the HG group. A DRP1-specific inhibitor, mdivi-1, suppressed mitochondrial fission and mitophagy, as well as restored mitochondrial functions in the HG condition. Moreover, the interaction of F-actin and DRP1 was enhanced in the diabetic group. Inhibiting F-actin with cytochalasin D repaired the injured effects of HG on mitochondrial dynamics and functions. Conversely, the F-actin-polymerization-inducer jasplakinolide aggravated mitochondrial fission and dysfunction.

CONCLUSIONS

F-actin contributes to HG-evoked mitochondrial fission by interacting with DRP1, which induces mitophagy and impairs mitochondrial function in SMG cells, ultimately damaging the SMG.

18F-PSMA-1007 salivary gland dosimetry: comparison between different methods for dose calculation and assessment of inter- and intra-patient variability

OBJECTIVE

Simplified calculation approaches and geometries are usually adopted for salivary
glands (SGs) dosimetry. Our aims were i) to compare different dosimetry methods to calculate
SGs absorbed doses (ADs) following [18F]-PSMA-1007 injection, and ii) to assess the AD
variation across patients and single SG components.
Approach: Five patients with prostate cancer underwent sequential PET/CT acquisitions of
the head and neck, 0.5, 2 and 4 hours after [18F]-PSMA-1007 injection. Parotid and
submandibular glands were segmented on CT to derive SGs volumes and masses, while PET
images were used to derive Time-Integrated Activity Coefficients. Average ADs to single SG
components or total SG (tSG) were calculated with the following methods: i) direct Monte
Carlo simulation with GATE/GEANT4 considering radioactivity in the entire PET/CT field-of-view (MC) or in the SGs only (MCsgo); ii) spherical model (SM) of OLINDA/EXM 2.1,
adopting either patient-specific or standard ICRP89 organ masses (SMstd); iii) ellipsoidal
model (EM); iv) MIRD approach with organ S-factors from OLINDA/EXM 2.1 and OpenDose
collaboration, with or without contribution from cross irradiation originating outside the SGs.
The maximum percent AD difference across SG components (δmax) and across patients (∆max)
were calculated.
Main results: Compared to MC, ADs to single SG components were significantly
underestimated by all methods (average relative differences ranging between -11.9% and -30.5%). δmax values were never below 25%. The highest δmax (=702%) was obtained with
SMstd. Concerning tSG, results within 10% of the MC were obtained only if cross-irradiation
from the remainder of the body or from the remainder of the head was accounted for. The ∆max
ranged between 58% and 78% across patients.
Significance: Simple geometrical models for SG dosimetry considerably underestimated ADs
compared to MC, particularly if neglecting cross-irradiation from neighboring regions. Specific masses of single SG components should always be considered given their large intra- and inter-patient variability.

The submandibular and sublingual glands maintain oral microbial homeostasis through multiple antimicrobial proteins

Introduction

Oral microbial homeostasis is a key factor affecting oral health, and saliva plays a significant role in maintaining oral microbial homeostasis. The submandibular gland (SMG) and sublingual gland (SLG) together produce the most saliva at rest. Organic ingredients, including antimicrobial proteins, are rich and distinctive and depend on the type of acinar cells in the SMG and SLG. However, the functions of the SMG and SLG in maintaining oral microbial homeostasis have been difficult to identify and distinguish, given their unique anatomical structures.

Methods

In this study, we independently removed either the SMG or SLG from mouse models. SMGs were aseptically removed in three mice in the SMG-removal group, and SLGs were aseptically removed in three mice in the SLG-removal group. Three mice from the sham-operated group were only anesthetized and incised the skin. After one month, we analyzed their oral microbiome through 16S rRNA sequencing. And then, we analyzed each gland using proteomics and single-cell RNA sequencing.

Results

Our study revealed that the microbiome balance was significantly disturbed, with decreased bacterial richness, diversity, and uniformity in the groups with the SMG or SLG removed compared with the sham-operated group. We identified eight secreted proteins in the SMG and two in the SLG that could be involved in maintaining oral microbial homeostasis. Finally, we identified multiple types of cells in the SMG and SLG (including serous acinar, mucinous acinar, ductal epithelial, mesenchymal, and immune cells) that express potential microbiota homeostasis regulatory proteins. Our results suggest that both the SMG and SLG play crucial roles in maintaining oral microbial homeostasis via excretion. Furthermore, the contribution of the SMG in maintaining oral microbial homeostasis appears to be superior to that of the SLG. These findings also revealed the possible antimicrobial function of gland secreta.

Discussion

Our results suggest that control of oral microbial dysbiosis is necessary when the secretory function of the SMG or SLG is impaired. Our study could be the basis for further research on the prevention of oral diseases caused by microbial dysbiosis.

Possible radioprotection of submandibular glands in gamma-irradiated rats using kaempferol: a histopathological and immunohistochemical study

BACKGROUND AND PURPOSE

Salivary gland damage remains a problem despite advances in radiotherapy schedules for head and neck cancer. Kaempferol, a natural flavonoid, found in several fruits and vegetables, is a good antioxidant. This study was designed to evaluate the possible protective effects of kaempferol on submandibular glands (SMGs) of rats exposed to fractionated gamma irradiation.

MATERIALS AND METHODS

Twenty-four male adult Wistar albino rats were included in this study and assigned to three groups (n = 8). Rats in group K received kaempferol orally in five doses at a dose of 10 mg/kg/2 days for 10 days. Meanwhile, rats in group R were subjected to fractionated whole-body gamma irradiation at a dose of 2 Gy/5 days/week for 2 weeks (20 Gy), and the KR group received kaempferol as group K and then was subjected to a fractionated whole-body gamma irradiation as group R. SMG samples were collected on days 1 and 7 after the last radiation session; and processed for histopathological and immunohistochemical investigations.

RESULTS

The SMGs of group R showed focal atrophy and degeneration. Acini showed vacuolization and had pyknotic hyperchromatic nuclei. Striated ducts degenerated, shrunken, and were surrounded by empty spaces. The percentage of areas covered by cyclooxygenase-2 (COX-2) significantly increased, whereas the percentage of areas covered by proliferating cell nuclear antigen (PCNA) significantly decreased compared with those in group K. Cotreatment with kaempferol (group KR) partially preserved normal gland architecture where acinar vacuolation and degeneration were almost absent; however, some ducts degenerated. A significant decrease in the percentage of areas covered by COX-2 and a significant increase in the percentage of areas covered by PCNA were observed compared with those in group R.

CONCLUSIONS

Kaempferol has a possible radioprotective effect on the SMGs of rats exposed to fractionated gamma irradiation.

MR-Guided Adaptive Radiotherapy for Head and Neck Cancer: Prospective Evaluation of Migration and Anatomical Changes of the Major Salivary Glands

The aim of this study was to quantify anatomical changes of parotids and submandibular glands and evaluate potential dosimetric advantages during weekly adaptive MR-guided radiotherapy (MRgRT) for the definitive treatment of head and neck cancer (HNC). The data and plans of 12 patients treated with bilateral intensity-modulated radiotherapy for HNC using MR-linac, with weekly offline adaptations, were prospectively evaluated. The positional and volumetric changes of the salivary glands were analyzed by manual segmentation in weekly MRI images and the dosimetric impact of these anatomical changes on the adapted treatment plans was assessed. The mean volume change in parotid and submandibular gland volume was -31.9% (p < 0.0001) and -29.7% (p < 0.0001) after five weeks, respectively. The volume change was significantly correlated with the cumulative dose for the respective gland at the time of volume measurement. Inter-parotid distance changed by -5.4% (6.5 mm) on average after five weeks (p = 0.0005). The distance became significantly smaller only in the left-right direction. The inter-submandibular gland distance changed by 0.7 mm (p = 0.38). This study demonstrated significant changes in salivary gland volumes and position following daily MR guidance and weekly plan adaptation. Ongoing clinical trials will provide data on the clinical impact of these changes and novel MR-based adaptation strategies.

Salivary Lactoferrin Expression in a Mouse Model of Alzheimer's Disease

In the last few years, microbial infection and innate immune theories have been proposed as an alternative approach explaining the etiopathogenesis and origin of Alzheimer's disease (AD). Lactoferrin, one of the main antimicrobial proteins in saliva, is an important modulator of immune response and inflammation, and represents an important defensive element by inducing a broad spectrum of antimicrobial effects against microbial infections. We demonstrated that lactoferrin levels in saliva are decreased in prodromal and dementia stages of AD compared with healthy subjects. That finding seems to be specific to cerebral amyloid-β (Aβ) load as such observation was not observed in healthy elderly controls or those subjects with frontotemporal dementia. In the present study, we analysed salivary lactoferrin levels in a mouse model of AD. We observed robust and early reduction of lactoferrin levels in saliva from 6- and 12-month-old APP/PS1 mice. Because saliva is secreted by salivary glands, we presume that deregulation in salivary glands resulting in reduced salivary lactoferrin levels may occur in AD. To test this hypothesis, we collected submandibular glands from APP/PS1 mice, as well as submandibular gland tissue from AD patients and we analysed the expression levels of key components of the salivary protein signalling pathway. A significant reduction in M3 receptor levels was found along with decreased acetylcholine (Ach) levels in submandibular glands from APP/PS1 mice. Similarly, a reduction in M3 receptor levels was observed in human submandibular glands from AD patients but in that case, the Ach levels were found increased. Our data suggest that the ACh-mediated M3 signalling pathway is impaired in salivary glands in AD, resulting in salivary gland dysfunction and reduced salivary lactoferrin secretion.

Positive Selection and Gene Expression Analyses from Salivary Glands Reveal Discrete Adaptations within the Ecologically Diverse Bat Family Phyllostomidae

The leaf-nosed bats (Phyllostomidae) are outliers among chiropterans with respect to the unusually high diversity of dietary strategies within the family. Salivary glands, owing to their functions and high ultrastructural variability among lineages, are proposed to have played an important role during the phyllostomid radiation. To identify genes underlying salivary gland functional diversification, we sequenced submandibular gland transcriptomes from phyllostomid species representative of divergent dietary strategies. From the assembled transcriptomes, we performed an array of selection tests and gene expression analyses to identify signatures of adaptation. Overall, we identified an enrichment of immunity-related gene ontology terms among 53 genes evolving under positive selection. Lineage-specific selection tests revealed several endomembrane system genes under selection in the vampire bat. Many genes that respond to insulin were under selection and differentially expressed genes pointed to modifications of amino acid synthesis pathways in plant-visitors. Results indicate salivary glands have diversified in various ways across a functional diverse clade of mammals in response to niche specializations.

Dosimetry of Submandibular Glands on Xerostomia for Nasopharyngeal Carcinoma

PURPOSE

To investigate dosimetry of submandibular glands on xerostomia after intensity-modulated radiotherapy for nasopharyngeal carcinoma (NPC).

METHODS

From September 2015 to March 2016, 195 NPC patients were investigated. Xerostomia was evaluated at 12 months after treatment via the RTOG/EORTC system. The least absolute shrinkage and selection operator regression model was used to optimize feature selection for grades 2-3 xerostomia. Multivariable logistic regression analysis was applied to build a predicting model incorporating the feature selected in the least absolute shrinkage and selection operator regression model. Discrimination, calibration, and clinical usefulness of the predicting model were assessed using the C-index, calibration plot, and decision curve analysis.

RESULTS

The V30 of the parotid glands was selected based on the least absolute shrinkage and selection operator regression. The nomogram displayed good discrimination with a C-index of 0.698 (95% confidence interval [CI]: 0.626-0.771) and good calibration (model 1). Addition of the dosimetric parameters including the mean dose to the submandibular glands, V50 of the submandibular glands, and volume of the submandibular glands to the model 1 failed to show incremental prognostic value (model 2). The model 2 showed a C-index of 0.704 (95% CI: 0.632-0.776). Decision curve analysis demonstrated that the model 1 was clinically useful when intervention was decided at the possibility threshold of > 20%. Within this range, net benefit was comparable between the model 1 and model 2.

CONCLUSION

PGv30 was a major predictive factor of grades 2-3 xerostomia for NPC. In contrast, the mean dose to the submandibular glands, V50 of the submandibular glands, and volume of the submandibular glands were not independent predictive factors.

An Extraoral Surgical Approach to Treat Chronic Submandibular Sialolithiasis - A Case Series

Sialolithiasis is the most common cause of sialadenitis in the submandibular gland, in which the highest incidence of this condition occurs, among the major salivary glands. This could be explained by the anatomy of Wharton's duct, and the chemical composition of the saliva produced by this gland. There are several alternatives and techniques for the treatment of sialolithiasis, including lithotripsy, sialoendoscopy, and conservative removal of the sialoliths or complete removal of the submandibular gland, through the transoral and extraoral routes for access to the gland. To determine the form of treatment, characteristics such as topography, diameter, and location of the sialolith in the duct are observed. The aim of this case series was to show our experience gained in two clinical cases of submandibular gland excision through an extraoral approach, using the submandibular access technique. In addition, we discussed the cause of sialolithiasis in these patients and after follow-up, compared the clinical results we obtained with this technique with those reported in the current literature. The submandibular approach or Risdon access continues to be a safe approach to removing the submandibular gland, as it is a commonly used technique and obtained satisfactory results, as shown in these cases. However, the major disadvantages were the less favorable esthetic results and paralysis of the marginal mandibular branch of the facial nerve.

Mesenchymal Stem Cells Extract (MSCsE)-Based Therapy Alleviates Xerostomia and Keratoconjunctivitis Sicca in Sjogren's Syndrome-Like Disease

Sjogren’s syndrome (SS) is an autoimmune disease that manifests primarily in salivary and lacrimal glands leading to dry mouth and eyes. Unfortunately, there is no cure for SS due to its complex etiopathogenesis. Mesenchymal stem cells (MSCs) were successfully tested for SS, but some risks and limitations remained for their clinical use. This study combined cell- and biologic-based therapies by utilizing the MSCs extract (MSCsE) to treat SS-like disease in NOD mice. We found that MSCsE and MSCs therapies were successful and comparable in preserving salivary and lacrimal glands function in NOD mice when compared to control group. Cells positive for AQP5, AQP4, α-SMA, CK5, and c-Kit were preserved. Gene expression of AQP5, EGF, FGF2, BMP7, LYZ1 and IL-10 were upregulated, and downregulated for TNF-α, TGF-β1, MMP2, CASP3, and IL-1β. The proliferation rate of the glands and serum levels of EGF were also higher. Cornea integrity and epithelial thickness were maintained due to tear flow rate preservation. Peripheral tolerance was re-established, as indicated by lower lymphocytic infiltration and anti-SS-A antibodies, less BAFF secretion, higher serum IL-10 levels and FoxP3⁺ T_reg cells, and selective inhibition of B220⁺ B cells. These promising results opened new venues for a safer and more convenient combined biologic- and cell-based therapy.

Radioprotective effect of endogenous melatonin secretion associated with the circadian rhythm in irradiated rats

Purpose: We investigated the radioprotective effect of endogenous melatonin release at different times associated with the circadian rhythm on head and neck radiotherapy. Materials and methods: Two groups of animals were subjected daily to 8 Gy single fraction radiotherapy in the head and neck region from 5:00 to 6:00 (the morning group) or from 19:00 to 20:00 (the evening group). Corresponding untreated groups served as controls. Submandibular glands from rats sacrificed on the seventh day after irradiation were assessed biochemically and histopathologically. Melatonin, malondialdehyde and superoxide dismutase levels in blood collected immediately prior to irradiation were measured with rat-specific ELISA kits. Results: In irradiated rats, melatonin, malondialdehyde and superoxide dismutase levels were significantly higher in the evening group than in the morning group. In nonirradiated rats, melatonin and superoxide dismutase levels were significantly higher in the evening group than in the morning group. The areas of seromucous acinar cells were similar between the irradiated and nonirradiated evening groups, but the area was higher in the evening irradiated group than in the morning irradiated group. Conclusion: Consideration of endogenous melatonin secretion associated with the circadian rhythm may offer new therapeutic solutions for the complications of head and neck radiotherapy.

Salispheres from Different Major Salivary Glands for Glandular Regeneration

Dysfunctional salivary glands (SGs) are a clinical challenge due to the lack of effective treatments. Cell therapy with stem/progenitor cells may improve this situation by providing promising therapeutic solutions. Therefore, exploring abundant cellular sources is important. Three major pairs of SGs are located in different anatomic regions: the parotid glands, the submandibular glands, and the sublingual glands. Although SG stem/progenitor cells can be isolated and cultivated from all major SGs as salispheres, the differences among SG origins remain unclear. In this study, salispheres were successfully isolated from all major SGs. The salispheres demonstrated unique cellular features that originated from their native tissues. The characteristic expression profiles and cellular features of SG stem cells were demonstrated in all salispheres. When they were transplanted into irradiated animals, the salispheres were all capable of improving the saliva secretion that was disrupted by irradiation. Typical histologic structures could be observed in most parts of the treated glands, and the fibrotic environments of irradiated submandibular glands were remodeled by all salispheres regardless of origins. This study characterized the cellular features and in vivo effects of salispheres that were derived from different anatomic origins. The results suggest the possibility of functional redundancy among distinct pairs of major SGs, which is useful for the design of cell therapy to treat dysfunctional glandular organs.

Spontaneous Regression of Swollen Submandibular Glands in IgG4-Related Disease

Background

IgG4-related disease is a new clinical entity frequently associated with swelling of the submandibular glands (SMGs). The long-term outcome of SMG swelling without steroid therapy remains unknown.

Objective

To examine whether swollen SMGs spontaneously regress without steroid therapy in the context of IgG4-related disease and to identify biomarkers that can predict the spontaneous regression of SMG swelling.

Methods

The SMG volume of 49 patients diagnosed with IgG4-related disease was calculated by measuring the axial and coronal planes of computed tomography scans. The change in SMG volume over time was measured and examined by treatment regimen, clinical data, and serum complement level.

Results

We found 28 of 49 (57%) IgG4-related disease patients to have swollen SMGs, with 15 of 20 (75%) of the swollen SMGs regressing without steroid therapy. The time required for the SMGs swelling to regress was significantly shorter in the steroid therapy group than in the no-steroid therapy group. Serum complement components at the initial visit were significantly lower in the regressed SMG group than in the nonregressed SMG group.

Conclusion

We observed 75% of swollen SMGs spontaneously regressed in patients with IgG4-related disease. The time required for the swollen SMGs to regress was longer in patients without steroid therapy than in those with steroid therapy. Serum complement level could be used as a predictor for the spontaneous regression of swollen SMGs in patients with IgG4-related disease.

Feasibility of endoscopic submandibular ganglion neurectomy for drooling

We performed endoscopic transoral neurectomy of the submandibular and sublingual glands to treat drooling. We bilaterally operated two adult cases with treatment-resistant drooling. In these patients, conventional treatment had failed. Repeated botilinum toxin type A (BOTOX®, Abdi Ibrahim Pharmaceutical Company, Istanbul, Turkey) injections had been effective but were becoming less so. The patients benefited from surgery in that their saliva scores decreased. No issue emerged over 6 months of follow-up. Endoscopic transoral neurectomy of the submandibular and sublingual glands reduces saliva production and allows management of drooling in treatment-resistant patients. Laryngoscope, 127:1604-1607, 2017.

De novo myoepithelial carcinoma with multiple metastases arising from a submandibular salivary gland: A case report

Salivary gland carcinomas are rare tumors, representing ~0.5% of all malignancies. Myoepithelioma is also uncommon, representing ~1% of all salivary gland tumors. Myoepithelial carcinoma (MC) is even rarer, representing 0.2 to 0.6% of all salivary gland tumors. We herein report a case of MC with multiple metastases arising from a submandibular gland in a 71-year-old male patient and present the associated imaging findings. The patient was considered to have a de novo type of myoepithelial carcinoma, which is reportedly associated with higher malignancy than the transformation type of the disease (i.e., a malignant change from pleomorphic adenoma or myoepithelioma). This was reflected in the multiple lung and bone metastases sites and strong positivity for p53 and Ki-67.

Cross-sectional comparison of ultrasonography scoring systems for primary Sjogren's syndrome

To choose the best ultrasound scoring system for clinic practice, ultrasound was performed for 94 cases with suspected primary Sjogren's syndrome (pSS) and 3 US scoring systems created by Hocevar, Salaffi, Millic were employd to assess for bilateral parotid glands and submandibular glands. The US evaluation was blinded to the final diagnosis of pSS according to 2002 classification criteria. 44 cases were finally diagnosed with pSS, 14 were diagnosed with secondary Sjogren's syndrome, and 36 were diagnosed with Sicca syndromes. Hocevar's method had the best likelihood ratio and accuracy, but Milic's scoring system was recommended for its excellent balance between the diagnostic value and inter/intra observation agreement value.

[Cone beam CT radiographic diagnosis of submandibular radiopaque sialolithiasis]

OBJECTIVE

To investigate the radiographic features of submandibular sialiths in cone beam CT (CBCT) images.

METHODS

Eighty-four patients with submandibular radiopaque sialiths were included in this study. The clinical features of gender and age and the radiographic features on CBCT, including the number, morphology, size, and location, were recorded for further statistical analysis.

RESULTS

A total of 128 sialiths were detected from the 84 subjects; 22 subjects (26.19%) had multiple sialiths. The morphology of the sialiths was classified into five types: spot, round, spheroid, elongated, and irregular shapes. Among these types, the spheroid shape was the most frequently detected. A correlation was observed between the size of the sialiths and their location, with the large sialith located at the posterior portion of the duct. About 39.06% (50/128) of sialiths was located at the anterior portion of the duct, and 60.94% (78/128) was located at the posterior portion. The horizon- tal position of the sialith was significantly correlated with its vertical position (P < 0.0001).

CONCLUSION

The CBCT images showed important data for the evaluation, diagnosis, and treatment plan of the submandibular sialolithiasis.

Actions of adenosine A1 and A2 receptor antagonists on CFTR antibody-inhibited beta-adrenergic mucin secretion response

1. The cystic fibrosis gene protein, the cystic fibrosis transmembrane conductance regulator (CFTR) acts as a chloride channel and is a key regulator of mucin secretion. The mechanism by which 3-isobutyl-1-methylxanthine (IBMX) corrects the defect in CFTR mediated beta-adrenergic stimulation of mucin secretion has not been determined. The present study has investigated the actions of adenosine A1 and A2 receptor antagonists to determine whether ability to stimulate mucin secretion correlates with correction of CFTR antibody inhibited beta-adrenergic response and whether excessive cyclic AMP rise is required. 2. CFTR antibodies were introduced into living rat submandibular acini by hypotonic swelling. Following recovery, mucin secretion in response to isoproterenol was measured. 3. The adenosine A1 receptor antagonist, 8 cyclopentyltheophylline (CPT) was a less potent stimulator of mucin secretion than was the A2 receptor antagonist dimethylpropargylxanthine (DMPX). A concentration of CPT close to the Ki for A1 receptor antagonism (10 nM) did not stimulate mucin secretion. 4. DMPX, although a potent stimulator of mucin secretion, did not correct CFTR antibody inhibited mucin secretion. 5. CPT corrected defective CFTR antibody inhibited mucin secretion at a high (1 mM) concentration, suggesting a mechanism other than adenosine receptor antagonism. 6. DMPX potentiated the isoproterenol induced cyclic AMP rise, whereas CPT did not. 7. Correction of the defective CFTR mucin secretion response did not correlate with ability to stimulate mucin secretion and did not require potentiation of beta-adrenergic induced increases in cyclic AMP. This affords real promise for the development of a selective drug treatment for cystic fibrosis.