Saliva Secretion Research Articles

Ginsenoside Rg3 Alleviates Xerostomia in Orchiectomized Mice via AR/AQP5.

Sjögren's disease (SjD), an autoimmune inflammatory disease, is associated with reduced androgen levels. Testosterone replacement therapy alleviates SjD progression, but the exact mode of action is unclear and adverse effects are reported. Our present study found that dihydrotestosterone (DHT) enhances the transcription and expression of aquaporin 5 (AQP5) in human salivary gland epithelial cells via androgen receptor (AR) signaling. The DHT/AR complex binds to the androgen response element of the AQP5 promoter, upregulating AQP5 expression. Using orchiectomized mice, we observed that reduced levels of DHT resulted in hyposalivation and SjD progression. By screening compounds with similar structures to DHT, we identified that DHT-like ginsenoside Rg3, a natural product, upregulates AQP5 expression in salivary gland epithelial cells via binding with AR. The Rg3/AR complex acts like DHT/AR and binds to the androgen response element of the AQP5 promoter to promote AQP5 transcription in salivary gland epithelial cells. Gavage of Rg3 restored saliva secretion and submandibular gland morphology in orchiectomized and nonobese diabetic mice. Transcriptome analysis revealed that Rg3 treatment upregulates saliva secretion-related signaling and downregulates inflammation and immune activation-related signaling in the submandibular glands of orchiectomized mice. In conclusion, our results indicated that Rg3 restores androgen deficiency-triggered xerostomia via AR-mediated AQP5 upregulation.

Oral Functions and Various Cooking Methods Associated With Chewing-To-Swallowing Time in Community-Dwelling Older Adults.

Oral frailty in older adults can affect their eating efficiency, prolonging meal times, which can compromise food flavour. This study explored the association between cooking methods and chewing-to-swallowing time on the basis of different oral functions in older adults. This cross-sectional study involved 65 community-dwelling individuals aged ≥ 65 years. Chewing-to-swallowing time was measured as participants tested the textures of two ingredients-chicken breast and baby Chinese cabbage-prepared using four cooking methods (boiling, sous vide, confit and high-pressure). Oral frailty was determined by the following items: tooth count, bite force, saliva secretion rate, swallowing, tongue-lip motor function and oral hygiene. Regression models analysed the correlation between cooking methods and chewing-to-swallowing time under various oral functions. No differences in chewing-to-swallowing time were found for chicken prepared using the various cooking methods among older adults with oral frailty (all p > 0.05). However, for older adults without oral frailty had a shorter chewing-to-swallowing time for both sous vide (β = -1.06, p < 0.001) and confit chicken (β = -1.79, p = 0.003) than for boiled chicken. For older adults with oral frailty had a shorter chewing-to-swallowing time for sous vide (β = -0.06, p < 0.001) and high-pressure methods (β = -1.16, p < 0.001) than for boiled vegetable. For older adults without oral frailty had a shorter chewing-to-swallowing time for high-pressure methods (β = -0.83, p < 0.001) than for boiled vegetable. Under different oral functional conditions, cooking methods are associated with the chewing and swallowing times of older adults.

Histopathology of the tongue in a hamster model of COVID-19

ObjectiveWith altered sense of taste being a common symptom of coronavirus disease 2019 (COVID-19), the main objective was to investigate the presence and distribution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) within the tongue over the course of infection.MethodsGolden Syrian hamsters were inoculated intranasally with SARS-CoV-2 and tongues were collected at 2, 3, 5, 8, 17, 21, 35, and 42 days post-infection (dpi) for analysis. In order to test for gross changes in the tongue, the papillae of the tongue were counted. Paraffin-embedded thin sections of the tongues were labeled for the presence of SARS-CoV-2 antigen.ResultsThere was no difference in fungiform or filiform papillae density throughout the course of infection. SARS-CoV-2 antigen was observed in the vallate papillae taste buds (3–35 dpi) and autonomic ganglia (5–35 dpi), as well as in the serous and mucous salivary glands of the posterior tongue (2–42 dpi).ConclusionThe presence and distribution of SARS-CoV-2 suggest that the virus could cause taste disturbance by infecting the vallate papillae taste buds. This effect could be exacerbated by a diminished secretion of saliva caused by infection of the serous salivary glands and the autonomic ganglia which innervate them.

SHED-Derived Exosomes Ameliorate Sjögren's Syndrome-Induced Hyposalivation by Suppressing Th1 Cell Response via the miR-29a-3p/T-bet Axis.

Background: Sjögren's syndrome (SS), an autoimmune disease, was characterized by sicca syndrome and systemic manifestations, presenting significant treatment challenges. Exosomes, naturally derived nanoparticles containing bioactive molecules, have garnered interest in regenerative medicine. The present study aimed to elucidate the immunoregulatory properties and mechanism of exosomes obtained from the stem cells derived from human exfoliated deciduous teeth (SHED-exos) in SS-induced sialadenitis. Methods: SHED-exo nanoparticles were injected into submandibular glands (SMGs) of 14-week-old nonobese diabetic (NOD) mice, a classic animal model of SS. At 21 weeks, the saliva flow rate (SFR) was measured. Lymphocyte proportions were examined via flow cytometry. Inflammatory cytokine levels were examined by the Quantibody mouse Th1/Th2/Th17 array and ELISA. miR-29a-3p expression and its regulatory effect on T-bet was detected using FISH and luciferase reporter gene assay, respectively. Results: SHED-exos injected into SMGs increased SFR, reduced lymphocytic infiltration, and decreased inflammatory cytokine levels in serum, SMG tissues, and saliva. Mechanistically, SHED-exos suppressed the Th1 proportion in spleen lymphocytes in NOD mice. Exosomal miR-29a-3p targeted and suppressed T-bet expression, which is a Th1-specific transcription factor. In vitro, SHED-exos (but not miR-29a-3p-inhibited exosomes) decreased the level of Th1 differentiation and IFN-γ and TNF-α production. Furthermore, SHED-exos (but not miR-29a-3p-inhibited exosomes) blocked the increase in IFN-γ and TNF-α production induced by T-bet overexpression. In vivo, miR-29a-3p-inhibited exosomes neither increase saliva secretion in NOD mice nor decrease lymphocytic infiltration, T-bet expression, and IFN-γ and TNF-α levels in SMGs. Conclusion: SHED-exos suppress Th1 cell differentiation and response through the miR-29a-3p/T-bet axis, contributing to amelioration of SS-induced hyposalivation.

Chronic degenerative failure of salivary glands can be reversed through restoring mitochondrial function.

There are no therapies for reversing chronic organ degeneration. Non-healing degenerative wounds are thought to be irreparable, in part, by the inability of the tissue to respond to reparative stimuli. As such, treatments are typically aimed at slowing tissue degeneration or replacing cells through transplantation. Building on our previous studies showing acutely injured salivary glands, and specifically secretory acini, can be regenerated, we reveal that non-healing, degenerating murine salivary glands remain responsive to a neuromimetic (muscarinic) agonist with treatment resulting in the restoration of tissue. Not only is degenerated tissue structure and function returned to a homeostatic-like state, but this outcome is also sustained months after treatment termination. Furthermore, despite an eventual reduction in saliva secretion, the gland responds to a second round of treatment, fully regaining secretory function that resembles uninjured controls. Our findings suggest this rescue is due to a reversal of an aberrant de-differentiated acinar cell state and mitochondrial dysfunction through a muscarinic-calcium signaling pathway. Thus, these data challenge the concept that organ degeneration is irreversible and provides a readily testable therapeutic strategy for epithelial organ restoration that may significantly benefit a diversity of chronic disease conditions.

Exosomes of human adipose stem cells mitigate irradiation injury to salivary glands by inhibiting epithelial-mesenchymal transition through miR-199a-3p targeting Twist1 and regulating TGFβ1/Smad3 pathway.

Rationale: Currently, irradiation-injured salivary glands (IR-SG) lack effective clinical treatment options. Emerging treatments using exosomes (Exo) have shown promising outcomes for various diseases. However, the efficacy of exosome in treating IR-SG remains unexplored. This study aimed to use exosomes to restore IR-SG function and to explore their underlying mechanisms. Methods: Exosomes isolated from human adipose-derived stem cell (ADSC-Exo) were injected into C57BL/6 mice that had their salivary glands injured with 14Gy. RNA sequencing profiled differentially expressed miRNAs and mRNAs of IR-SG. Epithelial-mesenchymal transition (EMT) mechanisms were further examined using SMG-C6 cells. Results: Exo-treated mice had a 96% increase in saliva secretion, higher cell proliferation, upregulated tissue repair/regeneration genes, and preserved functional cells with fewer collagen fibers compared to saline-treated mice. Exo treatment increased the expression of epithelial cell markers while decreasing mesenchymal cell markers. Notably, miR-199a-3p was significantly upregulated in Exo-treated mice, promoting cell growth and reducing EMT. Twist1, an EMT transcription factor, was identified as a direct target of miR-199a-3p and confirmed by luciferase assays. Twist1 overexpression promoted EMT, but Exo treatment or Twist1 knockdown reduced EMT marker expression and inactivated the TGFβ1/Smad3 pathway. Conclusions: ADSC-Exo is a promising therapy for IR-SG, primarily by mitigating EMT through miR-199a-3p targeting Twist1 and regulating the TGFβ1/Smad3 pathway.

Involvement of metformin and aging in salivary expression of ACE2 and TMPRSS2.

SARS-CoV-2-related proteins, ACE2 and TMPRSS2, are determinants of SARS-CoV-2 infection. Although these proteins are expressed in oral-related tissues, their expression patterns and modulatory mechanisms in the salivary glands remain unknown. We herein showed that full-length ACE2, which has both a fully functional enzyme catalytic site and high-affinity SARS-CoV-2 spike S1-binding sites, was more highly expressed in salivary glands than in oral mucosal epithelial cells and the lungs. Regarding TMPRSS2, zymogen and the cleaved form were both expressed in the salivary glands, whereas only zymogen was expressed in murine lacrimal glands and the lungs. Metformin, an AMPK activator, increased stimulated saliva secretion and full-length ACE2 expression and decreased cleaved TMPRSS2 expression in the salivary glands, and exerted the same effects on soluble ACE2 (sACE2) and sTMPRSS2 in saliva. Moreover, metformin decreased the expression of beta-galactosidase, a senescence marker, and ADAM17, a sheddase of ACE2 to sACE2, in the salivary glands. In aged mice, the expression of ACE2 was decreased in the salivary glands, whereas that of sACE2 was increased in saliva, presumably by the up-regulated expression of ADAM17. The expression of TMPRSS2 in the salivary glands and sTMPRSS2 in saliva were both increased. Collectively, these results suggest that the protein expression patterns of ACE2 and TMPRSS2 in the salivary glands differ from those in other oral-related cells and tissues, and also that metformin and aging affect the salivary expression of ACE2 and TMPRSS2, which have the potential as targets for preventing the transmission of SARS-CoV-2.

Prevalence and Factors Associated with Hypersalivation in Schizophrenia Inpatients Treated with Clozapine: A Retrospective Study.

Background: Hypersalivation, or excessive production and secretion of saliva, can result from associated disorders or adverse drug reactions. It significantly impacts physical health, psychosocial well-being, and quality of life. Clozapine, a gold standard for treatment-resistant schizophrenia, is known to cause hypersalivation in some patients. Objectives: This study aimed to determine the prevalence of hypersalivation and identify factors associated with its occurrence in patients with schizophrenia treated with clozapine, either as monotherapy or in combination with other antipsychotics. Methods: This retrospective cohort study was conducted using medical records from inpatients diagnosed with schizophrenia at a tertiary psychiatric hospital. Data were collected from patients treated with clozapine between June 1, 2020, and December 31, 2020. Descriptive statistics were used to describe the prevalence of hypersalivation, and multiple logistic regression was performed to assess the association between hypersalivation and patient characteristics. Results: A total of 96 patients were included in the study, with a mean age of 44.03 years (SD = 13.27); 72.9% of the patients were male. The overall prevalence of hypersalivation was 14.6%, with 19.51% of patients on clozapine monotherapy and 10.91% of those on clozapine combined with other antipsychotics experiencing hypersalivation. Male sex appeared to reduce the risk for hypersalivation (adjusted OR: 0.36, 95% CI: 0.10-1.33, P = .13), while the use of electroconvulsive therapy (ECT) significantly increased the risk of hypersalivation (adjusted OR: 5.40, 95% CI: 1.22-24.02, P = .03). Other variables, including age, Body Mass Index (BMI), smoking status, alcohol consumption, clozapine dosage, and use of anticholinergics, were not significantly associated with hypersalivation. Conclusion: The prevalence of hypersalivation in schizophrenia inpatients treated with clozapine was 14.6%. Male sex was associated with a reduced risk of hypersalivation, while ECT use significantly increased the risk. These findings provide valuable insights for clinicians managing patients on clozapine, highlighting the need for careful monitoring, particularly in patients undergoing ECT.

Nicotinamide mononucleotide suppresses cellular senescence and increases aquaporin 5 expression in the submandibular gland of aged male mice to ameliorate aging-related dry mouth.

Dry mouth results from decreased saliva secretion due to aging or drug side effects. Decreased saliva secretion causes dryness in the oral cavity that makes swallowing difficult and increases the risk of aspiration pneumonia. There are few fundamental treatments for dry mouth. Here we investigated whether treatment of old mice with nicotinamide mononucleotide (NMN) improved factors associated with dry mouth. Young (16-week-old) and old (113-week-old) male mice were treated subcutaneously with saline or NMN (300mg/kg) once every two days for four weeks and saliva secretion was measured. The amount of nicotinamide adenine dinucleotide (NAD+) in salivary gland tissues was measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Gene expression in the intestinal tract and salivary glands was measured by real-time PCR. The population of cells with acetylation in the submandibular gland was quantified by immunohistological staining. SA-β-gal activity in the submandibular gland was measured to assess cell senescence. Statistical analysis was performed by one-way analysis of variance with Tukey post hoc analysis. The submandibular glands from old mice treated with NMN exhibited increased saliva secretion and NAD+ levels, which both decrease with aging. In addition, the submandibular glands from NMN-treated old mice had decreased acetylation, numbers of senescent cells, and levels of senescence-associated secretory phenotype (SASP) factors, which all increase with aging, as well as increased aquaporin5 (AQP5) mRNA expression. NMN administration may improve dry mouth by regulating cellular senescence in the submandibular gland and increasing expression of AQP5, a water channel involved in saliva secretion, to inhibit age-related decreases in saliva secretion. It is necessary to elucidate further mechanism and confirm its effectiveness in humans.

Early Alterations of Cytoskeletal Proteins Induced by Radiation Therapy in the Parenchymal Cells of Rat Major Salivary Glands: A Comparative Immunohistochemical Analysis.

Head and neck malignancies (HNMs) encompass a variety of cancers that affect the oral and para-oral tissues, the most common of which are squamous cell carcinomas. Radiotherapy is commonly used to treat these cancers, often involving radiation exposure to the salivary glands. This study aims to investigate the early impacts of radiotherapy on the internal microstructure of the salivary gland cells and identify which gland exhibits the highest level of radiosensitivity. Twelve male albino rats were divided into two groups (control group and experimental group subjected to radiotherapy). The experimental group underwent adaily dose of 5 Grays of radiotherapy for six days with a total dose of 30 Grays, targeting the salivary glands. One month later, the salivary gland complex was dissected and processed for histological analysis and cytokeratin 17 (CK17) immunostaining. Histological examination of the irradiated salivary glands revealed atrophic changes in the gland parenchyma, accompanied by the proliferation of dense fibrous stroma. The parenchymal components consisted of small serous acini with poorly defined lumens, many of which had been replaced by fatty tissue with the formation of duct-like structures. Immunohistochemical findings of control glands exhibited weak to mild CK17 expression in duct cells, with the staining pattern typically diffuse or localized to the basal region of the cell. Some serous acini and serous demilunes within mixed acini exhibited diffuse, weak to mild CK17 expression, whereas the mucous acinar cells showed no expression. Radiated major glands revealed moderate to strong CK17 expression in the duct and serous acinar cells (p<0.05). Two distinct expression patterns were identified: the first exhibited diffuse expression across the cells, while the second showed intense expression at the apical region with mild expression at the basal part. The positive immunostaining in control salivary glands suggests that small amounts of intermediate filaments are essential for saliva secretion. Radiotherapy significantly disrupts the cytokeratin arrangement and density in major salivary glands, impairing saliva production. The most prominent changes occurred in the submandibular gland, followed by the parotid gland, with the sublingual gland showing the least impact. However, CK17 intensity in acinar cells was highest in the parotid, then submandibular, and lowest in the sublingual gland. Further research is needed to assess the short- and long-term effects and potential for recovery over time.

Mastication of Carrots with Different Shapes Affects the Composition of the Salivary Proteome—A Pilot Study

Chewing is a sensorimotor activity that aims to prepare food for swallowing, in which saliva intervenes, moistening food particles, assisting in bolus formation, enzymatic digestion, and swallowing. This study investigated the effect of chewing carrots of different shapes on salivary secretion and protein profiles using 2-DE gel electrophoresis. Fifteen participants chewed sliced or grated carrots, or parafilm (non-food control), in a crossover design, with saliva samples collected before and after mastication. The results showed significant differences in salivation and saliva composition when chewing carrots vs. the control, with sliced carrots inducing greater changes: 37 protein spots, including amylase and immunoglobulin spots, 9 protein spots, and 1 protein spot were significantly altered after chewing sliced carrots, grated carrots, and parafilm, respectively. Mastication combined with the sensory properties of food had a greater effect on saliva secretion and salivary protein levels than mastication alone. Among carrot shapes, the results suggest that harder food textures, which require more chewing effort, lead to more pronounced changes in salivary protein profiles. These findings contribute to the understanding of how food shape and texture influence salivation and salivary proteome dynamics, with potential implications for oral digestion, food-related sensory experiences, and the personalisation of diets for individuals with a compromised chewing capacity.

Efficiency of chewing load deficiency correction in clinical dental practice

Weakening of the chewing act, typical for modern humans due to consumption of soft food, causes a deficit of chewing load and has a negative effect on the dental system. To combat hypodynamia of the masticatory apparatus with the aim of preventing destructive processes in its structures, a gnathotraining system was developed, including electrical stimulation of the masticatory muscles themselves in physiological parameters, which develops the effect of “imaginary chewing”, and gnathotraining using chewing gum. In addition, functional training of the masticatory apparatus using chewing exercises was proposed. Considering that chewing gum practically does not compensate for the deficit of chewing load observed in modern society, the staff of the Kazan State Medical University and the Kazan National Research Technological University developed the “Denta Fit” dental trainer and a dental training system. It has been established that dental and jaw training stimulates secretion of saliva, its mineralizing potential, functional resistance of tooth enamel, allows achieving a good level of oral hygiene, reduces the rate of increase in the intensity of dental caries, as well as the severity of muscular-articular disorders of the temporomandibular joints, enhances neuromuscular activity of the masticatory muscles and regional blood flow. In children with permanent bite, dental and jaw training maintains the hydrogen index (pH) of oral fluid at a neutral level and provides, in combination with a toothbrush, optimal hygienic dental care, contributes to the formation of a correct dental occlusion. Thus, the effects of increased neuromuscular activity of the masticatory muscles, as well as regional vascular tone, arising during dental and jaw training, indirectly indicate that the dental and jaw system receives adequate mechanical loads necessary for the normal functioning of all its links. The results of the conducted studies indicate the effectiveness and feasibility of using dental training to improve dental status, which serves as a new approach to the prevention and treatment of dental diseases.

Hydrogen peroxide disrupts the regulatory pathway of saliva secretion in two salivary acinar rat cell lines.

Secretion of saliva is controlled by autonomic nerve signals via regulation of Ca2+-dependent ion transport across acinar cell membranes. Oxidative stress may affect this process, leading to a decrease in saliva production. This study investigates elements of the Ca2+ regulatory pathway and their vulnerability to hydrogen peroxide-induced oxidative stress. Rat parotid and submandibular salivary gland acinar cell lines were exposed to different hydrogen peroxide concentrations to simulate oxidative stress. Cell viability and intracellular reactive oxygen species were measured, mRNA levels were assessed via RT-qPCR, and protein expression was studied using western blot and immunofluorescence microscopy. Elevated concentrations of hydrogen peroxide reduced cell viability and increased intracellular levels of reactive oxygen species and led to a decrease in cholinergic receptor muscarinic 3 and adrenoreceptor alpha 1A mRNA and protein levels in both cell lines. In parotid gland cells, both mRNA and protein levels of stromal interaction molecule 1 and Orai1 decreased with increasing concentrations of hydrogen peroxide. In contrast, in submandibular gland cells stromal interaction molecule 1 and Orai1 displayed differential mRNA and protein expression levels. Our study revealed that hydrogen peroxide exposure alters rat parotid and submandibular acinar cells, increasing reactive oxygen species and reducing autonomic receptor expression. Differential mRNA and protein expression of stromal interaction molecule 1 and Orai1 highlight complex oxidative stress effects on Ca2⁺ signaling. Most likely these effects will be deleterious to salivary secretion, but some effects may be protective.

Local and systemic humoral immune responses to Histophilus somni recombinant antigens administered intranasally and subcutaneously to dairy calves

Bovine respiratory disease (BRD) causes significant economic losses in dairy calves. Induction of an early immune response via parenteral vaccination is complicated by the interference of colostral immunity. In this study, we investigated early immunization against selected conserved bacterial antigens. Calves were vaccinated twice intranasally and then subcutaneously with Histophilus somni recombinant proteins (rOMP40 or rHsp60) mixed with one of two adjuvants: CpG ODN2007 or MPLA. The control group (Con) was treated with PBS. The first immunization was done between 24 and 48 h of life and then twice in two weeks intervals. Blood, nasal, and saliva secretion samples were collected directly before vaccination (S1–S3) and then on 42–44 (S4) and 59–61 (S5) day of life. Antibodies (IgG1/IgG2/IgM/IgA in serum; IgG1/IgA in secretions) against both vaccine antigens were quantified in all samples. Intranasal and subcutaneous vaccinations using the described formulas did not increase antibody reactivity against the tested proteins. The reactivity of serum IgG1, IgM, and IgA anti-rOMP40 antibodies was significantly higher in S1 in all groups than that in the other samplings (p˂0.01). Significant differences in the reactivity of serum anti-rOMP40 antibodies between groups were identified in S1 (IgA reactivity was higher in the CpG vs. MPLA group; p < 0.05), S4 (IgM reactivity was higher in Con vs. CpG group; p < 0.05), and S5 (IgG1 reactivity was higher in MPLA vs. Con group; p < 0.05). The lack of consistent changes in antibodies after immunization (S4 and S5) hinders the drawing of conclusions regarding the effect of immunization on antibody reactivity. In the future, establishing a proper immunization window and adjuvants for nasal vaccines against bacterial pathogens causing BRD in calves remains to be determined.

Prediction of Dry Mouth Condition Using Radiomics Features from Tongue Diagnosis Image

Xerostomia, commonly known as dry mouth, is characterized by reduced salivary secretion, which can lead to various oral health issues and discomfort. In this paper, we propose a novel, non-invasive method for predicting xerostomia through the analysis of tongue images. To predict salivary gland secretion from tongue images, we collected images from patients who visited the hospital with complaints of dry mouth and measured their saliva secretion. Features were extracted from these tongue images, and correlation analysis was performed using machine learning techniques to assess the relationship between the extracted features and measured saliva secretion. We obtained tongue images and saliva secretion measurements from 176 patients. Images were cropped to 100 × 100 pixels, resulting in 462 features. The dataset was divided into training and test sets, consisting of 160 and 16 samples, respectively. The correlation coefficients for the training and test datasets were 0.9496 and 0.9415, respectively, while the correlation coefficient for the entire dataset was 0.9482. The estimated linear equation was y = 0.9244x + 2.1664. This study aimed to predict salivary gland secretion based on tongue images. By extracting features from color images and employing a neural network machine learning model, we estimated salivary gland secretion. With a sufficiently large dataset of tongue images, further advancements in regression analysis using deep learning techniques could enhance the accuracy of these predictions.

TGFβ2-Driven Ferritin Degradation and Subsequent Ferroptosis Underlie Salivary Gland Dysfunction in Postmenopausal Conditions.

Despite the high incidence of dry mouth in postmenopausal women, its underlying mechanisms and therapeutic interventions remain underexplored. Using ovariectomized (OVX) mouse models, here this study identifies ferroptosis, an iron-dependent regulated cell death, as a central mechanism driving postmenopausal salivary gland (SG) dysfunction. In the OVX-SGs, TGFβ signaling pathway is enhanced with the aberrant TGFβ2 expression in SG mesenchymal cells. Intriguingly, TGFβ2 treatment reduces iron-storing ferritin levels, leading to lipid peroxidation and ferroptotic death in SG epithelial organoids (SGOs). Mechanistically, TGFβ2 promotes the autophagy-mediated ferritin degradation, so-called ferritinophagy. A notable overexpression of the type III TGFβ receptor (TβRIII) is found in the OVX-SGs and TGFβ2-treated SGOs, while the silencing of TβRIII mitigates the ferroptosis-mediated deleterious effects of TGFβ2 on SGOs. Finally, administration of ferroptosis inhibitor, Liproxstatin-1 (Lip-1), improves saliva secretion in OVX mice. Present findings collectively suggest a link between TGFβ signaling, ferroptosis, and SG injury, offering new therapeutic avenues for postmenopausal xerostomia.

Adhesive lipophilic gels delivering rapamycin prevent oral leukoplakia from malignant transformation

Oral leukoplakia (OLK) is the most emblematic oral potentially malignant disorder that may precede the diagnosis of oral squamous cell carcinoma (OSCC) and has an overall malignant transformation rate of 9.8 %. Early intervention is crucial to reduce the malignant transformation rate from OLK to OSCC but the lack of effective local pharmaceutical preparations poses a challenge to clinical management. Rapamycin is speculated to prevent OLK from carcinogenesis and its inherent lipophilicity facilitates its penetration into stratum corneum. Nevertheless, hydrophilic hydrogels frequently encounter challenges when attempting to deliver lipophilic drugs. Furthermore, the oral cavity presents a complex environment defined by oral motor functions, saliva secretion cycles, dynamic fluctuations, and protective barriers comprising mucus and lipid layers. Consequently, addressing issues of muco-penetration and muco-adhesion is imperative for developing an effective drug delivery system aiming at delivering rapamycin to target oral potentially malignant disorders.Here, a dual-function hydrogel drug delivery system integrating adhesion and lipophilicity was successfully developed based on polyvinyl alcohol (PVA) and dioleoyl phosphatidylglycerol (DOPG) via dynamic boronic ester bonds. Rheological experiments based on orthogonal design revealed that PVA-DOPG hydrogels exhibited ideal adhesive strength (around 6 kPa) and could adhere to various surfaces in both dry and wet conditions. PVA-DOPG hydrogels also significantly promoted lipophilic molecules’ penetration into stratum corneum (integrated fluorescence density of 6.95 ± 0.52 × 106 and mean fluorescence depth of 0.96 ± 0.07 mm) of ex-vivo porcine buccal mucosa (p < 0.001). Furthermore, PVA-DOPG hydrogels incorporating rapamycin inhibited malignant transformation of OLK mouse model induced by 4-Nitroquinoline N-oxide (4-NQO), distinct improvements in survival (the neoplasm incidence density at the 40th day is 0.0091) (p < 0.05), decrease in neoplasm incidence density of 36.36 % and inhibition rate in neoplasm volume of 75.04 ± 33.67 % have been demonstrated, suggesting the hydrogels were valuable candidates for potential applications in the management of OLK.

Apigenin alleviates Sjögren’s syndrome-induced salivary gland epithelial cell ferroptosis via ERα signaling-mediated regulation of the ATF3/SLC7A1l axis

BackgroundIn Sjögren’s syndrome (SS)—an autoimmune disease characterized by dry mouth and eyes—salivary gland epithelial cells (SGECs) undergo ferroptosis, which disrupts their integrity and impairs saliva secretion. Apigenin, a phytoestrogen, is known to activate estrogen signalling and alleviate xerostomia in ovariectomized mice; however, its effect on SGEC survival and function in SS remains unclear. We hypothesized that apigenin alleviates SS symptoms and progression by inhibiting ferroptosis in SGECs and aimed to elucidate the underlying mechanism. MethodsApigenin (50 mg/kg) was orally gavaged to non-obese diabetic (NOD)/LtJ female mice (SS model); changes in SS functional indicators were analyzed using mRNA sequencing and bioinformatic analyses of submandibular glands. Interferon-gamma (IFN-γ)-stimulated SGECs were used to model SS in vitro; SGEC activity and aquaporin 5 (AQP5) expression were analyzed. Immunohistochemical staining, transmission electron microscopy, RT-qPCR, western blotting and other methods were used to verify the mechanisms. ResultsApigenin significantly increased salivary secretion and AQP5 expression while inhibiting ferroptosis and immune infiltration in NOD mouse submandibular glands. The oxidative stress gene ATF3 was upregulated and GPX4 was downregulated in NOD mice compared to that in control group (ICR mice); however, apigenin reversed this effect. IFN-γ treatment downregulated AQP5, SLC7A11, and GPX4 expression while promoting ATF3 expression and ferroptosis, which was mitigated by apigenin. ATF3 knockdown increased SLC7A11 and GPX4 expression, inhibiting SS and ferroptosis. Furthermore, apigenin inhibited ferroptosis in SGECs through ESR1 binding to ATF3. ConclusionApigenin alleviates SS by regulating SGEC ferroptosis via the ERα-regulated ATF3/SLC7A11 axis, highlighting its therapeutic potential in SS.

The involvement of aquaporin 5 in the inflammatory response of primary Sjogren's syndrome dry eye: potential therapeutic targets exploration.

Sjogren's syndrome (SS) is a chronic autoimmune disease. Mainly due to the infiltration of lymphoplasmic cells into the exocrine glands, especially the salivary glands and lacrimal glands, resulting in reduced tear and saliva secretion. Reduced tear flow can trigger Sjogren's syndrome dry eye (SSDE). Although the pathophysiology of SSDE xerosis remains incompletely understood, recent advances have identified aquaporin-5 (AQP5) as a critical factor in dysregulation of the exocrine gland and epithelium, influencing the clinical presentation of SSDE through modulation of inflammatory microenvironment and tear secretion processes. This review aims to explore AQP5 regulatory mechanisms in SSDE and analyze its potential as a therapeutic target, providing new directions for SSDE treatment.

Dysregulated Ca2+ signaling, fluid secretion, and mitochondrial function in a mouse model of early Sjögren's disease.

The molecular mechanisms leading to saliva secretion are largely established, but factors that underlie secretory hypofunction, specifically related to the autoimmune disease Sjögren's syndrome (SS) are not fully understood. A major conundrum is the lack of association between the severity of salivary gland immune cell infiltration and glandular hypofunction. SS-like disease was induced by treatment with DMXAA, a small molecule agonist of murine STING. We have previously shown that the extent of salivary secretion is correlated with the magnitude of intracellular Ca2+ signals (Takano et al., 2021). Contrary to our expectations, despite a significant reduction in fluid secretion, neural stimulation resulted in enhanced Ca2+ signals with altered spatiotemporal characteristics in vivo. Muscarinic stimulation resulted in reduced activation of the Ca2+-activated Cl- channel, TMEM16a, although there were no changes in channel abundance or absolute sensitivity to Ca2+. Super-resolution microscopy revealed a disruption in the colocalization of Inositol 1,4,5-trisphosphate receptor Ca2+ release channels with TMEM16a, and channel activation was reduced when intracellular Ca2+ buffering was increased. These data indicate altered local peripheral coupling between the channels. Appropriate Ca2+ signaling is also pivotal for mitochondrial morphology and bioenergetics. Disrupted mitochondrial morphology and reduced oxygen consumption rate were observed in DMXAA-treated animals. In summary, early in SS disease, dysregulated Ca2+ signals lead to decreased fluid secretion and disrupted mitochondrial function contributing to salivary gland hypofunction.