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.

Chronic Phenotypes Underlying Radiation-Induced Salivary Gland Dysfunction.

Head and neck cancer (HNC) is the sixth most diagnosed cancer, and treatment typically consists of surgical removal of the tumor followed by ionizing radiation (IR). While excellent at controlling tumor growth, IR often damages salivary glands due to their proximity to common tumor sites. Radiation damage to salivary glands results in loss of secretory function, causing severe and chronic reductions in salivary flow. This leads to the patient-reported sensation of dry mouth, termed xerostomia, which significantly reduces quality of life for HNC patients and survivors. The mechanisms underlying salivary gland damage remain elusive, and therefore, treatment options are scarce. Available therapies provide temporary symptom relief, but there is no standard of care for permanent restoration of function. There is a significant gap in understanding the chronic mechanistic responses to radiation as well as treatments that can be given in the months to years following cessation of treatment. HNC cases are steadily rising; particularly, the number of young patients diagnosed with nonfatal human papillomavirus + HNC continues to increase. The growing number of HNC diagnoses and improved prognoses results in more people living with xerostomia, which highlights the mounting need for restorative treatments. Mechanisms underlying chronic damage include decreases in acinar differentiation markers, increases in acinar cell proliferation, immune and inflammatory dysregulation, and metabolic changes including increases in amino acids and reductions in glycolysis and oxidative phosphorylation, fibrosis, and dysregulated neuronal responses. Currently, promising treatment options include adenoviral gene transfers and stem cell therapy. Thus, this review describes in depth known mechanisms contributing to chronic damage and discusses therapeutic advances in treating chronically damaged glands. Understanding the chronic response to radiation offers potential in development of new therapeutics to reverse salivary gland damage and improve the quality of life of HNC survivors.

The impact of submandibular glands protection on xerostomia as monitored by diffusion-weighted imaging in nasopharyngeal carcinoma patients.

PURPOSE: To determine the impact of sparing submandibular glands (SMGs) on alleviating xerostomia and the functional dynamics of the irradiated parotid glands (PGs) and sublingual glands (SLGs) by diffusion-weighted imaging. METHODS: 97 participants underwent 9 rounds of DWI scans before IC (pre-IC), pre-radiation (pre-RT), the midpoint of radiation (mid-RT), the end of radiation (post-RT), 1, 3, 6, 9, 12 (12m-RT) months following radiation. Apparent diffusion coefficient of SMGs (ADCSMG), PGs (ADCPG), and SLGs (ADCSLG), xerostomia questionnaire scores (XQ), and saliva flow rate measures under unstimulated (uSFR) and stimulated condition (sSFR) were documented. RESULTS: ADCPG, ADCSMG, ADCSLG, and XQ showed a rapid increase with a top at 3m-RT followed by regression, whereas uSFR and sSFR had the reverse trend. The change rate of ADC correlated with the dose to PGs, SMGs, and SLGs, as well as uSFR, sSFR, and XQ scores (p < 0.05 for all, except for uSFR with ADCPG (p = 0.063)). Maingroup for ADCPG, uSFR, and sSFR were significant (p values were 0.028, 0.000, 0.000 respectively); ADCPG in SMG sparing group was lower while uSFR, and sSFR were higher than those in the SMG-unsparing group. Simplegroup for ADCSMG, ADCSLG (all p < 0.05 from mid-RT to 12m-RT), and XQ (all p < 0.001 at mid-, 6m-, 9m-, and 12m-RT) were significant; ADCSMG, ADCSLG, and XQ were lower in the SMG-sparing group. CONCLUSIONS: SMG protection has a great impact on the functional retention of PGs and SLGs, resulting in alleviating xerostomia and improving quality of life. TRIAL REGISTRATION: The clinical trial was also registered with the Chinese Clinical Study Registry (registered number: ChiCTR1900024328, Date: July 6, 2019; URL: https://www.chictr.org.cn/showproj.aspx?proj=40726 ).

Fibrin hydrogels fortified with FGF-7/10 and laminin-1 peptides promote regeneration of irradiated salivary glands.

Ionizing radiation, commonly used for head and neck cancer treatment, typically damages the salivary glands, resulting in hyposalivation. The development of treatments to restore this lost function is crucial for improving the quality of life for patients suffering from this condition. To address this clinical need, we have developed an innovative hydrogel by chemically conjugating laminin-1 peptides (A99 and YIGSR) and growth factors, FGF-7 and FGF-10, to fibrin hydrogels. Our results demonstrate that FGF-7/10 and laminin-1 peptides fortified fibrin hydrogel [enhanced laminin-1 peptides fibrin hydrogel (Ep-FH)] promotes salivary gland regeneration and functionality by improving epithelial tissue organization, establishing a healthy network of blood vessels and nerves, while reducing fibrosis in a head and neck irradiated mouse model. These results indicate that fibrin hydrogel-based implantable scaffolds containing pro-regenerative signals promote sustained secretory function of irradiated salivary glands, offering a potential alternative treatment for hyposalivation in head and neck cancer patients undergoing radiation treatment. These unique findings emphasize the potential of fibrin hydrogel-based implantable scaffolds enriched with pro-regenerative signals in sustaining the secretory function of irradiated salivary glands and offer a promising alternative treatment for addressing hyposalivation in head and neck cancer patients undergoing radiation therapy. STATEMENT OF SIGNIFICANCE: Radiation therapies used to treat head and neck cancers often result in damaged salivary gland, leading to severe dryness of the oral cavity. In this study, we engineered FGF-7 and FGF-10 and immobilized them into L1p-FH. The resulting hydrogel, Ep-FH, restored irradiated salivary gland functionality by enhancing epithelial tissue organization, promoting the development of a healthy network of blood vessels and nerves as well as reduction of fibrosis.

Functional Analyses of Three Targeted DNA Antimicrobial Peptides Derived from Goats.

With the increase in drug-resistant bacteria, new antibacterial drugs have emerged as a prominent area of research and development. Antimicrobial peptides (AMPs), as innate immune agents, have garnered significant attention due to their potent, rapid, and broad-spectrum antibacterial activity. This study focused on investigating the functionality of three AMPs (CATH 1, CATH 2, and MAP34-B) derived from goat submandibular glands. Among these AMPs, CATH 2 and MAP34-B exhibited direct antibacterial activity against both Gram-negative and Gram-positive bacteria, primarily targeting the bacterial membrane. Additionally, these two AMPs were found to have the potential to induce reactive oxygen species (ROS) production in bacterial cells and interact with bacterial genome DNA, which may play a crucial role in their mechanisms of action. Furthermore, both CATH 1 and CATH 2 demonstrated significant antioxidant activity, and all three AMPs exhibited potential anti-inflammatory activity. Importantly, the cytotoxic activity of these AMPs against mammalian cells was found to be weak, and their hemolytic activity was extremely low. Overall, the characteristics of these three AMPs found in goat submandibular glands offer new insights for the study of host protection from an immunological perspective. They hold promise as potential candidates for the development of novel antibacterial agents, particularly in the context of combating drug-resistant bacteria.

A versatile genetic-encoded reporter for magnetic resonance imaging.

It has been a long-cherished wish in biomedicine research to have an imaging tool to visualize gene expression, with good spatiotemporal resolution, in rodent and primate animals noninvasively and longitudinally. To this purpose, we here present a novel genetic encoded magnetic resonance imaging reporter, i.e., GEM reporter, for noninvasive visualization of cell-specific gene expression. The GEM reporter was developed through codon modification of a bacteria-originated manganese (Mn) binding protein, allowing the sequestration of endogenous Mn in local tissues. When expressed in bacteria, plant and animals, GEM reporter can robustly produce high image contrast in T1-weighted MRI without additional substrates or contrast agents. Importantly, GEM reporter can be tracked inherently by MRI in specific cells and tissues. These findings support GEM reporter as a versatile marker for deciphering gene expression spatiotemporally in living subjects.

Artificial intelligence to predict outcomes of head and neck radiotherapy.

Head and neck radiotherapy induces important toxicity, and its efficacy and tolerance vary widely across patients. Advancements in radiotherapy delivery techniques, along with the increased quality and frequency of image guidance, offer a unique opportunity to individualize radiotherapy based on imaging biomarkers, with the aim of improving radiation efficacy while reducing its toxicity. Various artificial intelligence models integrating clinical data and radiomics have shown encouraging results for toxicity and cancer control outcomes prediction in head and neck cancer radiotherapy. Clinical implementation of these models could lead to individualized risk-based therapeutic decision making, but the reliability of the current studies is limited. Understanding, validating and expanding these models to larger multi-institutional data sets and testing them in the context of clinical trials is needed to ensure safe clinical implementation. This review summarizes the current state of the art of machine learning models for prediction of head and neck cancer radiotherapy outcomes.

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 positron-emission tomography/computed tomography (PET/CT) acquisitions of the head and neck, 0.5, 2 and 4 h 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 organS-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 (Δmax) 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%).δmaxvalues were never below 25%. The highestδmax(=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 Δmaxranged 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.

Current management of xerostomia in head and neck cancer patients.

Radiotherapy (RT) continues to play a key role in the management of head and neck cancer (HNC). Xerostomia remains a principal detriment to the quality of life (QoL) for 80 % of surviving patients receiving head and neck radiation. Radiation-induced injury to the salivary glands is dose-dependent, and thus efforts have been focused on decreasing radiation to the salivary glands. Decreased saliva production reduces both short-term and long-term quality of life in head and neck survivors by impacting on taste and contributing to dysphagia. Several radioprotective agents to the salivary gland have been investigated. Although not widely practiced, surgical transfer of the submandibular gland prior to RT is the mainstay of surgical options in preventing xerostomia. This review focuses on the strategies to improve xerostomia following radiation therapy in head and neck cancers.

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.

Complemental Diagnosis of IgG4-Related Pancreaticobiliary Diseases by Multiple Hypoechoic Lesions in the Submandibular Glands.

The diagnosis of autoimmune pancreatitis (AIP) and immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) may require a somewhat invasive pathological examination and steroid responsiveness. This retrospective study assessed the complemental diagnosis of AIP and IgG4-SC using submandibular gland (SG) ultrasonography (US) in 69 patients, including 54 patients with AIP, 2 patients with IgG4-SC, and 13 patients with both AIP and IgG4-SC. The data from the physical examination and US of SGs to diagnose AIP (n = 67) and IgG4-SC (n = 15) were analyzed. The steroid therapy efficacy in resolving hypoechoic lesions in SGs was evaluated in 36 cases. The presence of IgG4-related pancreaticobiliary disease with multiple hypoechoic lesions in SGs was reduced from 31 to 11 cases after steroid therapy, suggesting that multiple hypoechoic lesions in SGs are strongly associated with IgG4-positive cell infiltrations. Multiple hypoechoic lesions in SGs were observed in 53 cases, whereas submandibular swelling on palpation was observed in 21 cases of IgG4-related pancreaticobiliary diseases. A complemental diagnosis of IgG4-related pancreaticobiliary diseases without a histological diagnosis and steroid therapy was achieved in 57 and 68 cases without and with multiple hypoechoic lesions in SGs, respectively. In conclusion, multiple hypoechoic lesions in SGs are useful for the complemental diagnosis of IgG4-related pancreaticobiliary diseases.

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.

Feasibility and safety of neck level IB-sparing radiotherapy in nasopharyngeal cancer: a long-term single institution analysis.

PURPOSE: Nasopharyngeal cancer (NPC) has a higher prevalence of regional nodal metastasis than other head and neck cancers; however, level IB lymph node involvement is rare. We evaluated the safety and feasibility of level IB-sparing radiotherapy (RT) for NPC patients. MATERIALS AND METHODS: We retrospectively reviewed 236 patients with NPC who underwent definitive intensity-modulated RT with or without chemotherapy between 2004 and 2018. Of them, 212 received IB-sparing RT, and 24 received non-IB-sparing RT. We conducted a propensity score matching analysis to compare treatment outcomes according to IB-sparing status. In addition, dosimetric analysis of the salivary glands was performed to identify the relationship between xerostomia and the IB-sparing RT. RESULTS: The median follow-up duration was 78 months (range, 7 to 194 months). Local, regional, and distant recurrences were observed in 11.9%, 6.8%, and 16.1% of patients, respectively. Of the 16 patients with regional recurrence, 14 underwent IB-sparing RT. The most common site categorization of regional recurrence was level II (75%), followed by retropharyngeal lymph nodes (43.8%); however, there was no recurrence at level IB. In the matched cohorts, IB-sparing RT was not significantly related to treatment outcomes. However, IB-sparing RT patients received a significantly lower mean ipsilateral and contralateral submandibular glands doses (all, p < 0.001) and had a lower incidence of chronic xerostomia compared with non-IB-sparing RT patients (p = 0.006). CONCLUSION: Our results demonstrated that IB-sparing RT is sufficiently safe and feasible for treating NPC. To reduce the occurrence of xerostomia, IB-sparing RT should be considered without compromising target coverage.

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-ß (Aß) 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.

Dental pulp-derived stem cell-conditioned media attenuates secondary Sjögren's syndrome via suppression of inflammatory cytokines in the submandibular glands.

INTRODUCTION: Sjögren's syndrome (SS) is a chronic inflammatory autoimmune disease, which affects the exocrine glands. Its primary symptoms are decreased moisture in the mouth and eyes. Therapies are limited to treatment with steroids, which has unpleasant side effects, so new treatments would be beneficial. One possibility might be stem cells, such as bone marrow mesenchymal stem cells (BMMSCs) or dental pulp-derived stem cells (DPSCs); these have been reported to exert immunomodulatory effects on activated lymphoid cells. This study aimed to evaluate the effects of conditioned media from DPSCs (DPSC-CM) or BMMSCs (BMMSC-CM) on salivary functions in SS. METHODS: Cytokine array analysis was performed to assess the types of cytokines present in the media. DPSC-CM or BMMSC-CM was administered in an SS mouse model. Histological analysis of the salivary glands was performed, and gene expression levels of inflammatory and anti-inflammatory cytokines in the submandibular glands (SMGs) were evaluated. RESULTS: DPSC-CM contained more anti-inflammatory factors than BMMSC-CM. The mice that were given DPSC-CM had a lower number of inflammation sites in the SMGs than those in the other experimental groups, and their salivary flow rate increased. The expression levels of interleukin (IL)-10 and transforming growth factor-ß1 increased in the DPSC-CM group, while those of Il-4, Il-6, and Il-17a decreased. The mice that received DPSC-CM showed a significantly increased percentage of regulatory T cells and a significantly decreased percentage of type T helper 17 cells compared to other groups. CONCLUSIONS: These results indicate that DPSC-CM could be an effective therapy for SS-induced hyposalivation, since it decreases the number of inflammatory cytokines and regulates the local inflammatory microenvironment in the SMGs.

Relationship between dry mouth and hypertension.

OBJECTIVES: Salivary dysfunction, such as reduced salivary flow and an altered salivary composition, is caused by several diseases, medical conditions, and medications. The purpose of the present study was to clarify the relationship between hypertension and morphological changes in the submandibular glands. MATERIALS AND METHODS: An epidemiological study was conducted to elucidate the relationship between hypertension and dry mouth. The effects of hypertension on morphological changes and the intima thickness of arteries in the submandibular glands were histopathologically investigated. RESULTS: Among 1933 subjects in the epidemiological study, 155 (8.0%) had dry mouth. A multivariate analysis revealed that dry mouth correlated with age (p < 0.001), sex (p < 0.001), and hypertension (p < 0.05). No significant differences were observed in the size of the submandibular glands between patients with or without hypertension. The average area of acinar cells was smaller in patients with than in those without hypertension (0.366 ± 0.153 vs. 0.465 ± 0.178, p < 0.05). The arteriosclerotic index was significantly higher in patients with than in those without hypertension (0.304 ± 0.034 vs 0.475 ± 0.053, p < 0.05). CONCLUSIONS: Hypertension may contribute to the degeneration of the submandibular glands by decreasing the number of acinar cells and promoting fatty infiltration and stenosis of the arteries. CLINICAL RELEVANCE: There may be a correlation between hypertension and the degeneration of the submandibular glands by decreasing the number of acinar cells and promoting fatty infiltration and stenosis of the arteries.

Cell signaling regulation in salivary gland development.

The mammalian salivary gland develops as a highly branched structure designed to produce and secrete saliva. This review focuses on research conducted on mammalian salivary gland development, particularly on the differentiation of acinar, ductal, and myoepithelial cells. We discuss recent studies that provide conceptual advances in the understanding of the molecular mechanisms of salivary gland development. In addition, we describe the organogenesis of submandibular glands (SMGs), model systems used for the study of SMG development, and the key signaling pathways as well as cellular processes involved in salivary gland development. The findings from the recent studies elucidating the identity of stem/progenitor cells in the SMGs, and the process by which they are directed along a series of cell fate decisions to form functional glands, are also discussed. Advances in genetic tools and tissue engineering strategies will significantly increase our knowledge about the mechanisms by which signaling pathways and cells establish tissue architecture and function during salivary gland development, which may also be conserved in the growth and development of other organ systems. An increased knowledge of organ development mechanisms will have profound implications in the design of therapies for the regrowth or repair of injured tissues. In addition, understanding how the processes of cell survival, expansion, specification, movement, and communication with neighboring cells are regulated under physiological and pathological conditions is critical to the development of future treatments.

Production of functional human nerve growth factor from the submandibular glands of mice using a CRISPR/Cas9 genome editing system.

Nerve growth factor (NGF) is an essential trophic factor for the growth and survival of neurons in the central and peripheral nervous systems. For many years, mouse NGF (mNGF) has been used to treat various neuronal and non-neuronal disorders. However, the biological activity of human NGF (hNGF) is significantly higher than that of mNGF in human cells. Using the CRISPR/Cas9 system, we constructed the transgenic mice expressing hNGF specifically in their submandibular glands. As demonstrated by fluorescence immunohistochemical staining, these mice produced hNGF successfully, with 0.8 mg produced per gram of submandibular glands. hNGF with 99% purity was successfully extracted by two-step ion-exchange chromatography and one-step size-exclusion chromatography from the submandibular glands of these transgenic mice. Further, the purified hNGF was verified by LC-MS/MS. We analyzed the NH2-terminus of hNGF using both Edman degradation and LC-MS/MS-based methods. Both results showed that the obtained hNGF lost the NH2-terminal octapeptide (SSSHPIFH). Moreover, the produced hNGF demonstrated a strong promotion in the proliferation of TF1 cells.

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.