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.

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 ).

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.

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.

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.

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.

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-ß1, MMP2, CASP3, and IL-1ß. 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+ Treg 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.

Salivary glands and human congenital cytomegalovirus infection: What happens in early fetal life?

Salivary glands are a site of human cytomegalovirus (CMV) replication, latency, and persistence. Prolonged secretion of virus in saliva for months following a primary infection contribute to horizontal transmission. In order to better understand the early effects of CMV on salivary glands and the mechanisms of viral persistent replication, submandibular glands of six CMV congenitally infected fetuses at 21 weeks gestation were studied. Three fetuses at the same gestational age from CMV-seronegative women were compared as negative controls. Tissue viral load and the type of inflammatory infiltrate were evaluated. Moreover, development and branching of salivary glands, the number of myoepithelial cells, cellular proliferation, and expression of secretory proteins of the saliva (Gross Cystic Disease Fluid Protein-15 and lysozyme) were studied. A low viral load and rare CMV-positive cells associated with T CD8 cytotoxic lymphocytes were observed. Branching was impaired with a decrease in terminal acinar structures, the number of myoepithelial cells, and cellular proliferation were reduced. In addition, a compromised secretion of defense proteins involved in the oral humoral immunity was observed. These findings suggest that CMV may affect salivary glands, impairing structure development and secretion of defense proteins, probably responsible for the prolonged viral shedding in saliva. J. Med. Virol. 89:318-323, 2017. © 2016 Wiley Periodicals, Inc.

Metastatic retinoblastoma of the parotid and submandibular glands: a rare case report.

BACKGROUND: Retinoblastoma is the most common intraocular malignancy occurring in children. It can metastasize to the regional lymph nodes, central nervous system and distant organs usually the bones and bone marrow and very rarely to the soft tissue. Here, we report a case of unilateral retinoblastoma in a 4-year-old girl accompanied by a large metastasis of the parotid and submandibular glands that developed about 6 months previously and gradually increased in size 5 months after enucleation of the left eye. CASE PRESENTATION: A 4-year-old girl with a history of unilateral retinoblastoma presented with a large, painful and worsening mass (about 20 × 23 cm) of the left side of the neck. Following surgery, the orbital tumour was completely resected, and the large tumour invasion range in the left side of the neck was not resected completely. Histopathological examination revealed retinoblastoma of the orbit and the parotid and submandibular glands. After chemotherapy and additional local radiotherapy on the parotid and submandibular glands, the tumour was inactive and stable. CONCLUSIONS: Delayed detection and inappropriate management contribute to poor outcomes. Fundus examinations, education regarding the early signs of RB, and optimization of the therapeutic strategy for RB may play important roles in ocular health.

Polymicrobial infection alter inflammatory microRNA in rat salivary glands during periodontal disease.

Periodontal disease initiated by subgingival pathogens is linked with diminished secretion of saliva, and implies pathogenic bacteria dissemination to or affects secondary sites such as the salivary glands. MicroRNAs activated in response to bacteria may modulate immune responses against pathogens. Therefore, Sprague-Dawley rats were infected by oral lavage consisting of polymicrobial inocula, namely Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola, or sham-infected for 12 weeks (n = 6). We quantified inflammatory miRNA expression levels of miRNA-132, miR-146a, and miR-155 at secondary sites to the primary infection of the gingiva, including submandibular salivary glands, lacrimal glands, and pancreas. The presence of bacteria was detected in situ at secondary sites. Infected rat gingiva showed increased relative expression of miR-155. In contrast, miRNA-155 expression was decreased in submandibular salivary glands, along with positive identification of P. gingivalis in 2/6 and T. denticola in 1/6 rat salivary glands. Furthermore, miRNA-132 and miRNA-146a were significantly decreased in the pancreas of infected rats. This study is the first to show primary periodontal infections can alter miRNA profiles in secondary sites such as the salivary gland and pancreas. Whether these alterations contribute to pathologies of salivary glands in Sjögren's syndrome or of pancreas in diabetes warrants further investigation.