Resveratrol improves salivary dysfunction in a non-obese diabetic (NOD) mouse model of Sjögren's syndrome

Resveratrol Attenuates the Mitochondrial RNA-Mediated Cellular Response to Immunogenic Stress

Human mitochondria contain a circular genome that encodes 13 subunits of the oxidative phosphorylation system. In addition to their role as powerhouses of the cells, mitochondria are also involved in innate immunity as the mitochondrial genome generates long double-stranded RNAs (dsRNAs) that can activate the dsRNA-sensing pattern recognition receptors. Recent evidence shows that these mitochondrial dsRNAs (mt-dsRNAs) are closely associated with the pathogenesis of human diseases that accompany inflammation and aberrant immune activation, such as Huntington's disease, osteoarthritis, and autoimmune Sjögren's syndrome. Yet, small chemicals that can protect cells from a mt-dsRNA-mediated immune response remain largely unexplored. Here, we investigate the potential of resveratrol (RES), a plant-derived polyphenol with antioxidant properties, on suppressing mt-dsRNA-mediated immune activation. We show that RES can revert the downstream response to immunogenic stressors that elevate mitochondrial RNA expressions, such as stimulation by exogenous dsRNAs or inhibition of ATP synthase. Through high-throughput sequencing, we find that RES can regulate mt-dsRNA expression, interferon response, and other cellular responses induced by these stressors. Notably, RES treatment fails to counter the effect of an endoplasmic reticulum stressor that does not affect the expression of mitochondrial RNAs. Overall, our study demonstrates the potential usage of RES to alleviate the mt-dsRNA-mediated immunogenic stress response.

Effects of polyphenols in non-centrifugal cane sugar on saliva secretion: in vitro and in vivo experiments and a randomized controlled trial

This study examined the bioactivities and mechanisms of the non-centrifugal cane sugar polyphenols saponarin, schaftoside, and isoschaftoside in the salivary gland and their effects on salivation. In acute isolated C57BL/6N mouse submandibular gland cells, these polyphenols led to a higher increase in intracellular calcium after stimulation with the muscarinic agonist carbachol. Stimulation of these cells with polyphenols enhanced ATP production, aquaporin-5 translocation to the plasma membrane and eliminated intracellular reactive oxygen species generated by H₂O₂. In addition, phosphorylation of endothelial nitric oxide synthase and increased nitric oxide production in vascular endothelial cells were observed. In vivo administration of these polyphenols to C57BL/6N male mice resulted in significantly increased blood flow (saponarin, p = 0.040; isoschaftoside, p = 0.010) and salivation (saponarin, p = 0.031). A randomized controlled trial showed that intake of non-centrifugal cane sugar significantly increased saliva secretion compared with placebo (p = 0.003). These data suggest that non-centrifugal cane sugar polyphenols affect several pathways that support salivation and increase saliva secretion by enhancing vasodilation. Hence, non-centrifugal cane sugar polyphenols can be expected to maintain saliva secretion and improve reduced saliva flow.

Blueberry Leaf Extract Prevents Lacrimal Hyposecretion in Sjögren's Syndrome-like Model of Non-obese Diabetic Mice

BACKGROUND/AIM

This study evaluated the effect of blueberry leaf hot water extract (BLEx) on Sjögren's syndrome (SS)-like lacrimal hyposecretion in male non-obese diabetic (NOD) mice.

MATERIALS AND METHODS

NOD or BALB/c mice were fed 1% BLEx or control (AIN-93G) for 2 weeks from the age of 4 to 6 weeks. Pilocarpine-induced tear volume was measured using a phenol red-impregnated thread. The lacrimal glands were evaluated histologically by H&E staining. The IL-1β and TNF-α levels in the lacrimal gland tissue were measured by ELISA. The mRNA expression levels of secretion-related proteins were measured by real-time PCR. LC3 I/II and arginase 1 expression levels were measured by western blot.

RESULTS

After feeding with BLEx, pilocarpine-induced tear secretion in NOD mice was increased. In contrast, the mRNA expression levels of the cholinergic muscarinic M3 receptor, aquaporin 5, and ion channels related to lacrimal secretion were not changed by BLEx administration. In addition, the protein expression of arginase 1, which was recently reported to be involved in tear hyposecretion in NOD mice, was also not improved by BLEx administration. Although infiltration in the lacrimal gland of NOD mice was not decreased, the levels of TNF-α and the autophagy-related protein LC3 were significantly suppressed by BLEx treatment.

CONCLUSION

BLEx treatment may ameliorate lacrimal hyposecretion in NOD mice by delaying the progression of autoimmune disease by suppressing autophagy in lacrimal glands.

Bioinformatics analysis identified immune infiltration, risk and drug prediction models of copper-induced death genes involved in salivary glands damage of primary Sjögren's syndrome

This study aimed to identify copper-induced death genes in primary Sjögren's syndrome (pSS) and explore immune infiltration, risk and drug prediction models for salivary glands (SGs) damage. The 3 datasets, including GSE40611, GSE23117, and GSE7451 from the Gene Expression Omnibus database were downloaded. The datasets were processed using the affy in R (version 4.0.3). In immune cells, copper-induced death genes were strongly expressed in "activated" dendritic cells (aDCs), macrophages and regulatory T cells (Treg). In immune functions, copper-induced death genes were strongly expressed in major histocompatibility complex (MHC) class I, human leukocyte antigen (HLA) and type I interferon (IFN) response. Correlation analysis showed that 5 genes including SLC31A1, PDHA1, DLD, ATP7B, and ATP7A were significantly correlated with immune infiltration. The nomogram suggested that the low expression of PDHA1 was significant for predicting the risk of pSS and the area under curve was 0.678. Drug model suggested that "Bathocuproine disulfonate CTD 00001350," "Vitinoin CTD 00007069," and "Resveratrol CTD 00002483" were the drugs most strongly associated with copper-induced death genes. In summary, copper-induced death genes are associated with SGs injury in pSS, which is worthy of clinicians' attention.

Resveratrol alleviates salivary gland dysfunction induced by ovariectomy in rats

Resveratrol (Res), found abundant in many medicinal plants, exerts multiple biological functions in the body, including anti-inflammatory, antioxidant, and anti-aging properties. Xerostomia is a major symptom of salivary gland dysfunction in menopausal women, which significantly compromises the quality of life. Here, we investigated the effect of Res on estrogen deficiency-induced salivary gland dysfunction in rats. We found that Res administration could reduce body weight and water consumption, and increase salivary fluid secretion and blood flow of the submandibular gland. Furthermore, Res therapy alleviated histological lesions, increased AQP5 expression, and inhibited cell apoptosis in submandibular gland tissue. Meanwhile, the action of antioxidants was restored and the levels of inflammatory cytokines were attenuated by Res supplementation. Collectively, Res effectively improved estrogen deficiency-induced hyposalivation, which may provide a novel, safe, and practical approach to protect the salivary glands of estrogen-deficient females against xerostomia.

Adipose‑derived stem cells postpone the progression of Sjögren's syndrome by upregulating the Hippo signaling pathway

The aim of the present study was to explore the effect and mechanism of action of adipose-derived stem cells (ADSCs) on Sjögren syndrome (SS) to develop novel and more effective methods for SS treatment. ADSCs, dexamethasone or normal saline was injected into the submandibular gland (SMG) of three 12-week-old non-obese diabetic (NOD) mice. The degree of lymphocyte infiltration was considered as a criterion for judging disease progression, hematoxylin and eosin staining was performed to observe the pathological state, and the expression levels of TAZ, E-cadherin and α-catenin were assessed by western blotting. ADSC transplantation triggered an inhibitory effect on the progression of SS, which was slightly stronger compared with that of dexamethasone treatment. This was found to be related to the Hippo signaling pathway. In addition, TAZ protein expression levels decreased gradually with the progression of the disease; immunofluorescence staining showed that the expression of E-cadherin and TAZ followed similar trends. Notably, the expression of TAZ, p-TAZ, E-cadherin and α-catenin in NOD mice were lower compared with that in Control mice. Similarly, the ratio of p-TAZ/TAZ also decreased, which means that the activation level of Hippo signal pathway decreased. The results suggest that ADSCs may exert a therapeutic effect against SS and may postpone its progression by upregulating the Hippo signaling pathway.

A Possible Novel Protective Effect of Piceatannol against Isoproterenol (ISO)-Induced Histopathological, Histochemical, and Immunohistochemical Changes in Male Wistar Rats

Dry mouth is characterized by lower saliva production and changes in saliva composition. In patients with some salivary gland function remaining, pharmaceutical treatments are not recommended; therefore, new, more effective methods of promoting saliva production are needed. Hence, this study aimed to provide an overview of the histological changes in the salivary gland in the model of isoproterenol (ISO)-induced degenerative changes in male Wistar rats and to evaluate the protective effect of piceatannol. Thirty-two male Wistar rats were randomly divided into four groups: the control group, the ISO group, and the piceatannol (PIC)-1, and -2 groups. After the third day of the experiment, Iso (0.8 mg/100 g) was injected intraperitoneally (IP) twice daily into the animals. PIC was given IP in different daily doses (20 and 40 mg/kg) for three days before ISO and seven days with ISO injection. The salivary glands were rapidly dissected and processed for histological, histochemical, immunohistochemical (Ki-67), and morphometric analysis. Upon seven days of treatment with ISO, marked hypertrophy was observed, along with an increased number of positive Ki-67 cells. Proliferation was increased in some endothelial cells as well as in ducts themselves. Despite the significant decrease in proliferation activity, the control group did not return to the usual activity level after treatment with low-dose PIC. Treatment with a high dose of PIC reduced proliferative activity to the point where it was substantially identical to the results seen in the control group. An ISO-driven xerostomia model showed a novel protective effect of piceatannol. A new era of regenerative medicine is dawning around PIC’s promising role.

Polydatin Alleviates Diabetes-Induced Hyposalivation through Anti-Glycation Activity in db/db Mouse

Polydatin (resveratrol-3-O-β-mono-D-glucoside) is a polyphenol that can be easily accessed from peanuts, grapes, and red wine, and is known to have antiglycation, antioxidant, and anti-inflammatory effects. Diabetes mellitus is a very common disease, and diabetic complications are very common complications. The dry mouth symptom is one of the most common oral complaints in patients with diabetes mellitus. Diabetes mellitus is thought to promote hyposalivation. In this study, we aimed to investigate the improvement effect of polydatin on diabetes-induced hyposalivation in db/db mouse model of type 2 diabetes. We examined salivary flow rate, TUNEL assay, PAS staining, and immunohistochemical staining for AGEs, RAGE, HMGB1, 8-OHdG, and AQP5 to evaluate the efficacy of polydatin in the submandibular salivary gland. Diabetic db/db mice had a decreased salivary flow rate and salivary gland weight. The salivary gland of the vehicle-treated db/db mice showed an increased apoptotic cell injury. The AGEs were highly accumulated, and its receptor, RAGE expression was also enhanced. Expressions of HMGB1, an oxidative cell damage marker, and 8-OHdG, an oxidative DNA damage marker, increased greatly. However, polydatin ameliorated this hypofunction of the salivary gland and inhibited diabetes-related salivary cell injury. Furthermore, polydatin improved mucin accumulation, which is used as a damage marker for salivary gland acinar cells, and decreased expression of water channel AQP5 was improved by polydatin. In conclusion, polydatin has a potent protective effect on diabetes-related salivary gland hypofunction through its antioxidant and anti-glycation activities, and its AQP5 upregulation. This result suggests the possibility of the use of polydatin as a therapeutic drug to improve hyposalivation caused by diabetes.

Efficacy and safety of Resveratrol combined with Ablative Fractional CO2 laser system in the treatment of skin photoaging

OBJECTIVE

To evaluate the efficacy and safety of resveratrol combined with ablative fractional CO₂  laser system (AFL) treating skin photoaging.

METHODS

Thirty-two subjects were assigned to the treatment group (TG) or the control group (CG), respectively, applied test product (resveratrol essence) or control product twice daily for 6 months. Each subject was given an AFL treatment or no laser treatment on left or right side of the face randomly. Subjective evaluations by investigators and subjects themselves were conducted after treatment. Melanin index, erythema index, and cuticle moisture content were conducted at baseline and after treatments. Adverse events (AEs) were evaluated during the study period.

RESULTS

All subjects in TG achieved improvements of their photoaging signs compared to pre-treatment both the laser side and the non-laser side at 6 months (p < 0.05). On the laser side, TG produced a better improvement than CG at 6 months (p < 0.05). On the laser side, the difference values of MI in TG at the 2 months after enrollment (M2), M3, and M4 were more obvious than those in CG (p < 0.05). On the non-laser side, the difference values of MI in TG at M3, M4, M5, and M6 were more obvious than those of CG (p < 0.05). Subjects in TG were more likely to have tingling and had a faster subsidence of erythema mild edema, and pigmentation induced by AFL compared to CG.

CONCLUSION

The resveratrol can improve photoaging alone and add an efficacy to the AFL treatment and subside the AEs induced by AFL.

Pathology of salivary gland dysfunction and restoration of function

In this review, the author shows that simultaneous multiple disorders caused by reactivation of Epstein-Barr virus can lead to salivary gland disorders as part of Sjogren's syndrome (SS). Therefore, clinicians must differentiate SS from other diseases when diagnosing and treating salivary gland disorders. In particular, the author explains how microbial infection in SS overcomes immunological tolerance, leading to pathological changes, and how cytokine overexpression and endocrine disrupters contribute to glandular tissue injury. Also, the author suggests that involvement of reactive oxygen species is a common pathogenesis of salivary gland disorders and SS, so regulation of oxidative stress is an effective treatment for both. The results of clinical studies on restoring salivary gland function and regenerating salivary glands with tissue stem cells may provide clues on elucidating the cause of SS.

Epigenetics in Primary Sjögren's Syndrome

Primary Sjögren's syndrome (SjS) is a chronic and systemic autoimmune epithelitis with predominant female incidence, which is characterized by exocrine gland dysfunction. Incompletely understood, the etiology of SjS is multi-factorial and evidence is growing to consider that epigenetic factors are playing a crucial role in its development. Independent from DNA sequence mutations, epigenetics is described as inheritable and reversible processes that modify gene expression. Epigenetic modifications reported in minor salivary gland and lymphocytes from SjS patients are related to (i) an abnormal DNA methylation process inducing in turn defective control of normally repressed genes involving such matters as autoantigens, retrotransposons, and the X chromosome in women; (ii) altered nucleosome positioning associated with autoantibody production; and (iii) altered control of microRNA. Results from epigenome-wide association studies have further revealed the importance of the interferon pathway in disease progression, the calcium signaling pathway for controlling fluid secretions, and a cell-specific cross talk with risk factors associated with SjS. Importantly, epigenetic modifications are reversible thus opening opportunities for therapeutic procedures in this currently incurable disease.

Cordycepin attenuates Salivary Hypofunction through the Prevention of Oxidative Stress in Human Submandibular Gland Cells

Xerostomia (dry mouth) is a significant age-related condition. Meanwhile, cordycepin, the natural therapeutic agent, has demonstrated an anti-aging effect. Therefore, the present study aimed to investigate the preventive effects of cordycepin on secretory function in an in vitro model of hydrogen peroxide (H₂O₂)-induced salivary hypofunction. After being exposed to H₂O₂, human submandibular gland (HSG) cells were treated with various concentrations of cordycepin (6.25-50 µM) for 24, 48, and 72h. To evaluate cell proliferation and reactive oxygen species (ROS) generation, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and 2, 7'-dichlorodihydrofluorescein diacetate assays were performed. The amylase activity was kinetically measured by 2-chloro-p-nitrophenol linked with maltotrioside. The expression of salivary, antioxidant and apoptotic markers at mRNA and protein levels were performed by reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence analysis, respectively. We demonstrated that cordycepin (6.25-25 µM) contributed to significant increases in expression of the salivary marker genes, alpha-amylase 1 (AMY1A) and aquaporin-5 (AQP5), and in amylase secretion without changes in cell viability. Under oxidative stress, HSG cells showed remarkable dysfunction. Cordycepin rescued the protective effects partially by decreasing ROS generation and restoring the expression of the salivary proteins, AMY and AQP5 via anti-oxidant and anti-apoptotic activity. In addition, the amount of amylase that was secreted from HSG cells cultured in cordycepin was increased. In conclusion, cordycepin demonstrated a protective effect on H₂O₂ -induced HSG cells by decreasing ROS generation and upregulating the salivary function markers, AMY1A and AQP5, at both the transcriptional and translational levels.

Hyperglycemia and Salivary Gland Dysfunction in the Non-obese Diabetic Mouse: Caveats for Preclinical Studies in Sjögren's Syndrome

The Non-obese Diabetic (NOD) mouse model for type I diabetes also develops some features of Sjögren’s syndrome (SS). Since the source of the mice and the environment exert a strong influence on diabetes, this study investigated SS development in NOD mice obtained from two vendors. Female NOD mice from The Jackson Laboratory (JAX) and Taconic Biosciences were monitored for blood glucose and pilocarpine-induced salivation. The gut microbiome was analyzed by 16S rRNA sequencing of stool DNA. At euthanasia, serum cytokines and sialoadenitis severity were evaluated. The onset of diabetes was significantly accelerated in JAX mice compared to Taconic mice. Although the gut microbiome between the two groups was distinct, both groups developed sialoadenitis. There was no correlation between the severity of sialoadenitis and reduced saliva production. Instead, salivary gland dysfunction was associated with hyperglycemia and elevation of serum IL1β, IL16, and CXCL13. Our data suggest that inflammatory pathways linked with hyperglycemia are confounding factors for salivary gland dysfunction in female NOD mice, and might not be representative of the mechanisms operative in SS patients. Considering that NOD mice have been used to test numerous experimental therapies for SS, caution needs to be exerted before advancing these therapeutics for human trials.

Effect of gummy candy containing ubiquinol on secretion of saliva: A randomized, double-blind, placebo-controlled parallel-group comparative study and an in vitro study

A randomized, double-blind, placebo-controlled, parallel-group comparative clinical study was conducted to examine the effects of ubiquinol (the reduced form of Coenzyme Q10) on secretion of saliva. This interventional study enrolled 40 subjects aged 65 years or younger who were healthy, but noted slight dryness of the mouth. Subjects were randomized with stratification according to gender and age to ingestion of gummy candy containing 50 mg of ubiquinol or placebo twice daily for 8 weeks. At the end of study, along with a significant increase of the CoQ10 level in saliva (p = 0.025*, d = 0.65), there was a significant increase of the saliva flow rate (p = 0.048*, d = 0.66) in the ubiquinol candy group (n = 18; 47.4±6.2 years; 6 men and 12 women) compared to the placebo group (n = 20; 52.2±7.7 years; 4 men and 16 women). The strength of the stomatognathic muscles was not significantly enhanced by ingestion of ubiquinol candy. Compared with baseline, significant improvement of the following four questionnaire items was observed in the ubiquinol group at the end of the study: feeling tired (p = 0.00506, d = -0.726), dryness of the mouth (p = 0.04799, d = -0.648), prone to catching a cold (p = 0.00577, d = -0.963), and diarrhea (p = 0.0166, d = -0.855). There were no serious adverse events. An in vitro study revealed that ubiquinol stimulated a significant and concentration-dependent increase of ATP production by a cell line derived from human salivary gland epithelial cells (p<0.05), while 1 nM ubiquinol significantly suppressed (p = 0.028) generation of malondialdehyde by cells exposed to FeSO4-induced oxidative stress. These findings suggest that ubiquinol increases secretion of saliva by suppressing oxidative stress in the salivary glands and by promoting ATP production. Trial Registration: UMIN-CTR UMIN000024406.