The role of the epithelial-to-mesenchymal transition (EMT) in diseases of the salivary glands

Hypoxia Contributes to the Early-Stage Progression of Necrotizing Sialometaplasia

Necrotizing sialometaplasia (NSM) is a nonneoplastic lesion listed in the World Health Organization Classification of Tumours-Head and Neck Tumours. In early NSM lesion, there is infarction and necrosis of the acinar cells, and squamous metaplasia of the salivary ducts occurs as the lesion matures. Differentiation from squamous cell carcinoma and other malignancies is sometimes required clinically and histopathologically. Local hypoxia caused by trauma and vascular compromise is a proposed etiology of NSM. However, the mechanisms underlying the pathogenesis are unclear. This study focused on the early stages of NSM. Histopathologic observations revealed that the region showing acinar necrosis contained myoepithelial cells with reticular arrangement. Hypoxic in vitro experiments using mouse salivary gland organoids revealed that myoepithelial and basal cells were more tolerant to hypoxia than acinar cells. Moreover, the residual myoepithelial cells in NSM and hypoxia-tolerant cells in organoids expressed transforming growth factor-β3 (TGFB3), which plays a critical role in cell proliferation and squamous metaplasia. Organoid experiments have also replicated the process of squamous metaplasia in NSM during hypoxia and the resolution of hypoxia. Thus, this study demonstrated that hypoxia is a possible etiology of NSM based on the results of histopathologic and in vitro experimental observations.

Immune and non-immune mediators in the fibrosis pathogenesis of salivary gland in Sjögren's syndrome

Sjögren's syndrome (SS) or Sjögren's disease (SjD) is a systemic autoimmune disease clinically manifested as sicca symptoms. This disease primarily impacts the functionality of exocrine glands, specifically the lacrimal and salivary glands (SG). SG fibrosis, an irreversible morphological change, is a severe consequence that occurs in the later stages of the disease due to sustained inflammation. However, the mechanism underlying SG fibrosis in SS remains under-investigated. Glandular fibrosis may arise from chronic sialadenitis, in which the interactions between infiltrating lymphocytes and epithelial cells potentially contributes to fibrotic pathogenesis. Thus, both immune and non-immune cells are closely involved in this process, while their interplays are not fully understood. The molecular mechanism of tissue fibrosis is partly associated with an imbalance of immune responses, in which the transforming growth factor-beta (TGF-β)-dependent epithelial-mesenchymal transition (EMT) and extracellular matrix remodeling are recently investigated. In addition, viral infection has been implicated in the pathogenesis of SS. Viral-specific innate immune response could exacerbate the autoimmune progression, resulting in overt inflammation in SG. Notably, post-COVID patients exhibit typical SS symptoms and severe inflammatory sialadenitis, which are positively correlated with SG damage. In this review, we discuss the immune and non-immune risk factors in SG fibrosis and summarize the evidence to understand the mechanisms upon autoimmune progression in SS.

Metformin Attenuates Partial Epithelial-Mesenchymal Transition in Salivary Gland Inflammation via PI3K/Akt/GSK3β/Snail Signaling Axis

Chronic inflammation in the salivary glands (SG) often triggers epithelial-mesenchymal transition (EMT), leading to the loss of acinar function and promoting fibrosis. This study explores the role of Metformin in mitigating partial EMT in SG inflammation. In vitro, human salivary gland epithelial cells (hSGECs) were treated with lipopolysaccharide (LPS) and Metformin. EMT markers and the PI3K/Akt/GSK3β/Snail signaling axis were assessed using RNA-seq and Western blot analysis. In vivo, a Wharton's duct ligation rat model was employed to mimic chronic sialadenitis (CS). Nine Wistar rats were randomly divided into three groups: Control, Ligation and Ligation + Metformin groups, with three rats per group. After ductal ligation, the Ligation + Metformin group received 100 mg/kg of Metformin via intragastric administration, while the Control and Ligation groups received an equivalent saline every 24 h. Histological analysis, immunohistochemical and immunofluorescence staining were conducted to evaluate acinar morphology, EMT, and the PI3K/Akt/GSK3β/Snail signaling axis. The results showed that in CS tissues, atrophied acinar cells underwent partial EMT. In vitro, Metformin reversed LPS-induced EMT in hSGECs. RNA-seq and Western blot revealed that Metformin achieved this effect by targeting the PI3K/Akt/GSK3β/Snail signaling axis (P < 0.01). In ductal ligation models, Metformin treatment restored ligation-induced acinar damage and functional loss (P < 0.01). Further histological evidence supported that Metformin mitigated EMT by inhibiting inflammatory activation of PI3K/Akt/GSK3β/Snail signaling axis (P < 0.01). In conclusion, Metformin alleviates partial EMT in SG inflammation by targeting the PI3K/Akt/GSK3β/Snail signaling axis, highlighting its potential as a therapeutic strategy for SG inflammation.

Case report: A nodular lesion in the ventral region of the neck in the rat as a starting point for considerations on differential diagnosis

The purpose of this case report is to present a poorly differentiated sarcoma in a pet rat. A veterinarian detected a small-sized nodular lesion in the ventral region of the neck during a follow-up visit related to another ailment. The anatomical structures found in the neck region in the rat and the differential diagnosis when deformities are palpated in this body part are discussed in detail. The patient underwent a total of four surgical procedures, as well as radiotherapy and chemotherapy. The rat survived in good condition for 144 days after finding the tumor.

Is epithelial-mesenchymal transition related to the biological behavior of salivary gland neoplasms?

OBJECTIVE

To evaluate and compare the expression of E-cadherin, Snail1 and Twist1 in pleomorphic adenomas (PAs), adenoid cystic carcinomas (AdCCa) and carcinoma ex-pleomorphic adenomas (CaexPA) of salivary glands, as well as investigate possible associations with clinicopathological parameters.

STUDY DESIGN

E-cadherin, Snail1 and Twist1 antibody immunostaining were analyzed semiquantitatively in 20 PAs, 20 AdCCas and 10 CaexPAs. Cases were classified as low and high expression for analysis of the association with clinicopathological parameters.

RESULTS

Compared to PAs, AdCCas and CaexPAs exhibited higher nuclear expression of Snail1 (p = 0.021 and p = 0.028, respectively) and Twist1 (p = 0.009 and p = 0.001). Membranous and cytoplasmic expression of E-cadherin were positively correlated in PAs, AdCCas and CaexPAs (r = 0.645, p = 0.002; r = 0.824, p < 0.001; r = 0.677, p = 0.031). In PAs, positive correlation was found between nuclear expression of Snail1 and membrane expression of E-cadherin (r = 0.634; p = 0.003), as well as between nuclear expression of Snail1 and Twist1 (r = 0.580; p = 0.007). Negative correlations were detected between membrane expression of E-cadherin and cytoplasmic expression of Snail1 in AdCCas (r = - 0.489; p = 0.029).

CONCLUSIONS

E-cadherin, Twist1, and Snail1 may participate in modulating events related to cell differentiation and adhesion in PAs and to biological behavior in AdCCas and CaexPAs, which indicates the involvement of EMT in these processes. Furthermore, the expression of these proteins in these carcinomas may reflect the plasticity feature of EMT.

Tumor budding - a potential biomarker in low grade salivary gland carcinomas?

Background

Low-grade salivary gland carcinoma is regularly treated with surgical therapy of the salivary gland without elective neck dissection in T1/2 carcinomas, either alone or with adjuvant radiation therapy. However, occult metastasis and locoregional recurrence influence therapy and outcome. Tumor budding is an emerging prognostic pathological factor in many carcinomas, but has not yet been adequately considered in salivary gland carcinomas.

Methods

We conducted a retrospective single-center study of 64 patients diagnosed with low-grade carcinoma of the major salivary glands treated between 2003 and 2017. Pathological risk factors and TNM classification were thoroughly assessed for each case. All hematoxylin and eosin (HE)-stained histological specimens underwent careful examination, and tumor budding was identified following the guidelines set forth by the International Tumor Budding Consensus Conference in 2016.

Results

Tumor budding was not statistically significant concerning 5-year survival rate (5-YSR) (p=0.969) and mean overall survival (log-rank p=0.315). Whereas 5-year disease-free survival rate (5-YDFSR) was 87% in the low tumor budding group and 61.1% in the intermediate and high tumor budding group (p=0.021). Mean disease-free survival accounted for 100.2 months (CI: 88.6;111.9) in the low budding score group and 58.7 months (CI: 42.8;74.6) in the other group (log-rank p=0.032). Notably, pT1/2 showed significantly lower tumor buds than pT3/4 stages (2.43 tumor buds/0.785 mm2 vs. 4.19 tumor buds/0.785 mm2, p=0.034). Similar findings were noted comparing nodal-positive and nodal-negative patients, as well as patients with and without lymphovascular invasion and perineural invasion (each p<0.05).

Conclusions

Tumor budding might be used as an additional prognostic factor for recurrence in low-grade salivary gland carcinoma, seemingly associated with a higher nodal metastasis rate and advanced tumor stages and a worse 5-YDFSR. Consequently, the evaluation of tumor budding in resection specimens of low-grade salivary gland tumor may prove valuable in decision-making for neck dissection and follow-up strategy.

Exploring Salivary Epithelial Dysfunction in Sjögren's Disease

Sjögren's Disease (SjD) is an autoimmune disease of the exocrine tissues. Etiological events result in the loss of epithelial homeostasis alongside extracellular matrix (ECM) destruction within the salivary and lacrimal glands, followed by immune cell infiltration. In this review, we have assessed the current understanding of epithelial-mesenchymal transition (EMT)-associated changes within the salivary epithelium potentially involved in salivary dysfunction and SjD pathogenesis. We performed a PubMed literature review pertaining to the determination of pathogenic events that lead to EMT-related epithelial dysfunction and signaling in SjD. Molecular patterns of epithelial dysfunction in SjD salivary glands share commonalities with EMT mediating wound healing. Pathological changes altering salivary gland integrity and function may precede direct immune involvement while perpetuating MMP9-mediated ECM destruction, inflammatory mediator expression, and eventual immune cell infiltration. Dysregulation of EMT-associated factors is present in the salivary epithelium of SjD and may be significant in initiating and perpetuating the disease. In this review, we further highlight the gap regarding mechanisms that drive epithelial dysfunction in salivary glands in the early or subclinical pre-lymphocytic infiltration stages of SjD.

E-CADERIN, N-CADERIN, SLUG, SNAIL, and TWIST contribute to epithelial-mesenchymal transition in salivary gland tumors

BACKGROUND

Transcription factors are important in the epithelial-mesenchymal transition process and are possibly related to the development of a more invasive tumor phenotype. Thus, the objective of this study was to analyze the expression and identify the localization of cellular markers related to the epithelial-mesenchymal transition process in salivary gland tumors.

STUDY DESIGN

The expression and localization of E-CADERIN, N-CADERIN, SLUG, SNAIL, and TWIST were evaluated, using immunohistochemistry, in 48 salivary gland tumors, being 17 pleomorphic adenomas (PA), 14 adenoid cystic carcinomas (ACC), and 17 mucoepidermoid carcinomas (MEC). these proteins were compared to clinical and histopathologic parameters. normal gland tissues were included for immunohistochemical comparisons.

RESULTS

ACC and MEC cases showed higher expression of SNAIL compared to PA. MEC showed high expression of SLUG and TWIST. Low expression of N-CADHERIN, SNAIL, and TWIST in ACC was frequent in T3 and T4. High expression of TWIST in MEC was more frequent at age ≥ 40 years A positive correlation was only observed between N-cadherin/SNAIL in ACC, between SNAIL/TWIST in MEC, and between SLUG/TWIST in PA.

CONCLUSION

This study provided insight into EMT-related proteins (E-cadherin, N-cadherin, SNAIL, SLUG, and TWIST) and their contribution to the maintenance of morphogenesis and the development of the salivary gland tumors and showed a positive correlation among N-CADHERIN/SNAIL in ACC and SNAIL/TWIST in MEC.

High-grade intraductal carcinoma of the parotid gland harboring CTNNA1::ALK rearrangement: Changes in genetic status using genetic testing during treatment with an ALK inhibitor

BACKGROUND

Salivary gland carcinomas harboring anaplastic lymphoma kinase (ALK) rearrangements are rare. Here, we present the pathological characteristics, clinical course, and changes in the genetic status of a salivary gland carcinoma harboring a catenin alpha 1 (CTNNA1)::ALK rearrangement during treatment with an ALK tyrosine kinase inhibitor (TKI).

METHODS

A 59-year-old man with a parotid tumor and cervical lymph node metastases underwent total parotidectomy and radical neck dissection. One month after completion of postoperative radiotherapy, the patient experienced multiple recurrences.

RESULTS

Subsequent treatment with the ALK-TKI alectinib was initially effective against the intraductal carcinoma harboring CTNNA1::ALK rearrangement and TP53 mutation. However, 10 months later the patients' condition deteriorated, and an additional phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutation was detected. The patient ultimately succumbed to multiple organ failure.

CONCLUSION

The clinical course suggested the concurrent emergence of TP53 and PIK3CA mutations and ALK-TKI drug-selective growth of non-ALK rearrangement gene tumor cells.

Immunological and biological dissection of normal and tumoral salivary glands

Salivary glands naturally play central roles in oral immunity. The salivary glands microenvironment inevitable may be exposed to exogenous factors consequently triggering the initiation and formation of various malignant and benign tumors. Mesenchymal stem cells are recruited into salivary gland microenvironment, interact with tumor cells, and induce inhibitory cytokines as well as cells with immunosuppressive phenotypes such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). The immune components and tumor immune responses in malignant and benign SGTs are still under investigation. Immune responses may directly play a limiting role in tumor growth and expansion, or may participate in formation of a rich milieu for tumor growth in cooperation with other cellular and regulatory molecules. Immune checkpoint molecules (e.g. PDLs, HLA-G and LAG3) are frequently expressed on tumor cells and/or tumor-infiltrating lymphocytes (TILs) in salivary gland microenvironment, and an increase in their expression is associated with T cell exhaustion, immune tolerance and tumor immune escape. Chemokines and chemokine receptors have influential roles on aggressive behaviors of SGTs, and thereby they could be candidate targets for cancer immunotherapy. To present a broad knowledge on salivary glands, this review first provides a brief description on immunological functions of normal salivary glands, and then describe the SGT's tumor microenvironment, by focusing on mesenchymal stem cells, immune cell subsets, immune checkpoint molecules, chemokines and chemokine receptors, and finally introduces immune checkpoint inhibitors as well as potential targets for cancer therapy.

Maternal Fluoride Exposure Exerts Different Toxicity Patterns in Parotid and Submandibular Glands of Offspring Rats

There is currently a controversial and heated debate about the safety and ethical aspects of fluoride (F) used for human consumption. Thus, this study assessed the effects of prenatal and postnatal F exposure of rats on the salivary glands of their offspring. Pregnant rats were exposed to 0, 10, or 50 mg F/L from the drinking water, from the first day of gestation until offspring weaning (42 days). The offspring rats were euthanized for the collection of the parotid (PA) and submandibular (SM) glands, to assess the oxidative biochemistry and to perform morphometric and immunohistochemical analyses. F exposure was associated with a decrease in the antioxidant competence of PA in the 10 mg F/L group, contrasting with the increase observed in the 50 mg F/L group. On the other hand, the antioxidant competence of the SM glands was decreased at both concentrations. Moreover, both 10 and 50 mg F/L groups showed lower anti-α-smooth muscle actin immunostaining area in SM, while exposure to 50 mg F/L was associated with changes in gland morphometry by increasing the duct area in both glands. These findings demonstrate a greater susceptibility of the SM glands of the offspring to F at high concentration in comparison to PA, reinforcing the need to adhere to the optimum F levels recommended by the regulatory agencies. Such findings must be interpreted with caution, especially considering their translational meaning.

Sjögren's Syndrome-Related Organs Fibrosis: Hypotheses and Realities

Sjögren's syndrome (SS) is a systemic chronic autoimmune disorder characterized by lymphoplasmacytic infiltration of salivary glands (SGs) and lacrimal glands, causing glandular damage. The disease shows a combination of dryness symptoms found in the oral cavity, pharynx, larynx, and vagina, representing a systemic disease. Recent advances link chronic inflammation with SG fibrosis, based on a molecular mechanism pointing to the epithelial to mesenchymal transition (EMT). The continued activation of inflammatory-dependent fibrosis is highly detrimental and a common final pathway of numerous disease states. The important question of whether and how fibrosis contributes to SS pathogenesis is currently intensely debated. Here, we collect the recent findings on EMT-dependent fibrosis in SS SGs and explore clinical evidence of multi-organ fibrosis in SS to highlight potential avenues for therapeutic investigation.

Polarized Microscopic Analysis of Picrosirius Red Stained Salivary Gland Pathologies: An Observational Study

OBJECTIVE

 Salivary gland diseases and their pathologies may affect the glandular structure including collagen, a major stromal component, in response to tissue damage or diseases. This study aimed to examine the changes in collagens in different salivary gland diseases using polarized picrosirius red staining.

MATERIALS AND METHODS

 The submandibular gland samples diagnosed as sialadenitis, chronic sclerosing sialadenitis, pleomorphic adenoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma were stained with picrosirius red, Masson's trichrome, and anticollagen I staining. The quantity of collagens was examined and reported as a percentage of positive picrosirius red area. The maturity of collagens was studied with polarized light microscope and reported as a percentage of orange-red and yellow-green polarized collagens, representing the mature and immature collagens, respectively.

STATISTICAL ANALYSIS

 The % positive areas for picrosirius red representing the collagen amount among salivary gland diseases were analyzed by one-way analysis of variance with Tukey's test. The % orange-red and % yellow-green polarized areas representing the collagen maturity were analyzed by Kruskal-Wallis test and Mann-Whitney U test.

RESULTS

 The malignant tumors, adenoid cystic carcinoma (29.92) and mucoepidermoid carcinoma (26.59), had higher significant percentage of positive picrosirius red area, compared with the benign tumor (14.56), chronic sclerosing sialadenitis (10.61), and sialadenitis (7.22) (p < 0.05). The percentages of orange-red polarized areas are 48.07, 39.6, 62.67, 83.75, and 76.05 in sialadenitis, chronic sclerosing sialadenitis, pleomorphic adenoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma, respectively. This percentage tended to increase in the benign and malignant lesions with statistical difference, compared with the inflammatory lesions (p < 0.05). There was no statistical difference in the percentages of yellow-green polarized areas among various salivary gland diseases. In addition, the results of Masson's trichrome and anticollagen I staining are corresponding to that of picrosirius red among various salivary gland diseases.

CONCLUSIONS

 Polarized picrosirius red demonstrated the most amounts of collagen in the malignant lesion, and represented the different maturity of collagens in each lesion group. Studying the amounts and maturity of collagen with picrosirius red for extracellular matrix alteration in salivary gland diseases along with routine hematoxylin and eosin, Masson's trichrome, and immunohistochemistry may provide a better understanding in different salivary gland pathologies.

EMT in salivary gland tumors: the expression of microRNAs miR-155 and miR-200c is associated with clinical-pathological parameters

BACKGROUND

Epithelial to mesenchymal transition promotes cell adhesion loss, enabling invasion and metastasis. MicroRNAs are a class of small non-codifying RNAs that regulate gene expression.

OBJECTIVES

The aim of this study was to evaluate the expression of microRNAs that could regulate the expression of EMT factors in salivary gland tumors (SGTs).

METHODS AND RESULTS

The expression of microRNAs miR-9, miR-34a, miR-101, miR-138, miR-155, and miR-200c-described in the literature to target EMT factors-was evaluated by Real-time RT-PCR (qPCR) in pleomorphic adenoma (PA), mucoepidermoid carcinoma (MEC) and adenoid cystic carcinoma (ACC) samples. Bioinformatics tools were applied to identify miR targets and immunohistochemistry was used to examine the expression of the proteins E-cadherin, Twist, ZEB-1, β-Catenin, and c-Kit. Comparing miR expression among SGT types, we observed increased expression of miR-9, and miR-138 in PAs, and increased miR-155 expression in MECs. Low-grade MECs exhibited increased miR-155 expression (p = 0.032). MECs that generated lymph node metastases had increased miR-200c levels (p = 0.018). MECs tended to have decreased expression of EMT-related proteins when compared to the other SGT types (c-Kit p < 0.001, Twist p = 0.014, and ZEB p = 0.012). Notably, increased c-Kit expression was associated with the presence of perineural infiltration in ACC (p = 0.050).

CONCLUSIONS

This study provides evidence of alterations in the expression of EMT-factors regulating miRs, especially of miR-9, miR-138, miR-155, and miR-200c. No significant relationships were found between the expression of these miRs and proteins associated with EMT in SGTs.

Salivary Glands after Prolonged Aluminum Exposure: Proteomic Approach Underlying Biochemical and Morphological Impairments in Rats

Aluminum (Al) is one of the most abundant elements on Earth, and its high extraction rate and industrial use make human exposure very common. As Al may be a human toxicant, it is important to investigate the effects of Al exposure, mainly at low doses and for prolonged periods, by simulating human exposure. This work aimed to study the effects of low-dose exposure to chloride aluminum (AlCl₃) on the oxidative biochemistry, proteomic profile, and morphology of the major salivary glands. Wistar male rats were exposed to 8.3 mg/kg/day of AlCl₃ via intragastric gavage for 60 days. Then, the parotid and submandibular glands were subjected to biochemical assays, proteomic evaluation, and histological analysis. Al caused oxidative imbalance in both salivary glands. Dysregulation of protein expression, mainly of those related to cytoarchitecture, energy metabolism and glandular function, was detected in both salivary glands. Al also promoted histological alterations, such as acinar atrophy and an increase in parenchymal tissue. Prolonged exposure to Al, even at low doses, was able to modulate molecular alterations associated with morphological impairments in the salivary glands of rats. From this perspective, prolonged Al exposure may be a risk to exposed populations and their oral health.

Ketamine Induced Bladder Fibrosis Through MTDH/P38 MAPK/EMT Pathway

Purpose: Ketamine is an anesthetic in clinical, but it has also been used as an abusing drug due to its low price and hallucinogenic effects. It is proved that ketamine abusing would cause multiple system damage including the urinary system, which is called ketamine-induced cystitis (KIC). Bladder fibrosis is late stage in KIC and threaten abusers’ life. This study aimed to investigate the molecular mechanism of ketamine-induced bladder fibrosis.

Methods: Female Sprague Dawley (SD) rats were randomly divided into 3 groups. 2 groups were treated with tail vein injection of ketamine (25 mg/kg/day, 50 mg/kg/day ketamine hydrochloride solution, respectively) for 12 weeks, whereas the control group was treated with normal saline solution. In each group, rat bladders were extracted and samples were examined for pathological and morphological alterations via hematoxylin and eosin (HE) staining, Masson’s trichrome staining and immunohistochemistry (IHC). SV-HUC-1 cells were treated with different concentrations of ketamine solution (0, 0.1, 0.5, 1 mmol/L). Rat bladder and SV-HUC-1 cells were extracted protein and RNA for Western blot and RT-PCR detection. Metadherin (MTDH) siRNAs and overexpression plasmids were used to knock down and overexpress the relative genes. P38 mitogen-activated protein kinase (MAPK) inhibitor was utilized to inhibit the MAPK pathway.

Results: Rats in the ketamine group exhibited fibrosis compared to rats of the control group and fibrosis were also markedly upregulated in SV-HUC-1 cells after treated with ketamine, which were ketamine concentration-dependent. After treating with ketamine in SV-HUC-1 cells, there was an increase expression of MTDH, epithelial-mesenchymal transition (EMT) markers, P38 MAPK. MTDH knockdown would suppresses P38 MAPK/EMT pathway to inhibit fibrosis, however, MTDH overexpression could promote the pathway in SV-HUC-1 cells.

Conclusion: In rats and SV-HUC-1 cells ketamine-treated models, MTDH can regulate EMT through the P38 MAPK pathway to regulate the process of bladder fibrosis.

Methylmercury-Induced Toxicopathologic Findings in Salivary Glands of Offspring Rats After Gestational and Lactational Exposure

Methylmercury (MeHg) is one of the main global pollutants. The vulnerability of fetus and newborn to MeHg-induced changes is extensively reported, making relevant investigation possible for alternative sample matrix for human biological monitoring for at this stage of life. This study aimed to characterize tissue change effects of environmental-experimental MeHg on salivary glands of offspring rats after pre- and postnatal exposure. For this, pregnant Wistar rats were orally exposed to MeHg (40 μg/kg BW/day) or only vehicle (control group), from the gestational period to the end of the lactation period. Salivary glands (SG) were collected from the offspring to analyze possible Hg levels and main findings by histopathological evaluations and CK19 and α-SMA immunostaining. The results indicated that Hg levels in SG of intoxicated offspring were associated with histologic abnormalities, such as acinar atrophy and an increase in the intercellular matrix among the acini, as well as damages in the architecture of epithelium and myoepithelial cells, evidenced by a decrease in immunostaining area. Thus, this is the first study to show in the literature the toxicopathologic findings on SG of offspring after pre- and postnatal exposure to MeHg. Moreover, it presents the SG as an attractive target to futures studies, mainly in children exposed to environmentally relevant doses.

SMADS-Mediate Molecular Mechanisms in Sjögren's Syndrome

There is considerable interest in delineating the molecular mechanisms of action of transforming growth factor-β (TGF-β), considered as central player in a plethora of human conditions, including cancer, fibrosis and autoimmune disease. TGF-β elicits its biological effects through membrane bound serine/threonine kinase receptors which transmit their signals via downstream signalling molecules, SMADs, which regulate the transcription of target genes in collaboration with various co-activators and co-repressors. Until now, therapeutic strategy for primary Sjögren’s syndrome (pSS) has been focused on inflammation, but, recently, the involvement of TGF-β/SMADs signalling has been demonstrated in pSS salivary glands (SGs) as mediator of the epithelial-mesenchymal transition (EMT) activation. Although EMT seems to cause pSS SG fibrosis, TGF-β family members have ambiguous effects on the function of pSS SGs. Based on these premises, this review highlights recent advances in unravelling the molecular basis for the multi-faceted functions of TGF-β in pSS that are dictated by orchestrations of SMADs, and describe TGF-β/SMADs value as both disease markers and/or therapeutic target for pSS.

Organ Fibrosis and Autoimmunity: The Role of Inflammation in TGFβ-Dependent EMT

Recent advances in our understanding of the molecular pathways that control the link of inflammation with organ fibrosis and autoimmune diseases point to the epithelial to mesenchymal transition (EMT) as the common association in the progression of these diseases characterized by an intense inflammatory response. EMT, a process in which epithelial cells are gradually transformed to mesenchymal cells, is a major contributor to the pathogenesis of fibrosis. Importantly, the chronic inflammatory microenvironment has emerged as a decisive factor in the induction of pathological EMT. Transforming growth factor-β (TGF-β), a multifunctional cytokine, plays a crucial role in the induction of fibrosis, often associated with chronic phases of inflammatory diseases, contributing to marked fibrotic changes that severely impair normal tissue architecture and function. The understanding of molecular mechanisms underlying EMT-dependent fibrosis has both a basic and a translational relevance, since it may be useful to design therapies aimed at counteracting organ deterioration and failure. To this end, we reviewed the recent literature to better elucidate the molecular response to inflammatory/fibrogenic signals in autoimmune diseases in order to further the specific regulation of EMT-dependent fibrosis in more targeted therapies.

Resident CD34-positive cells contribute to peri-endothelial cells and vascular morphogenesis in salivary gland after irradiation

Salivary gland (SG) hypofunction is a common post-radiotherapy complication. Besides the parenchymal damage after irradiation (IR), there are also effects on mesenchymal stem cells (MSCs) which were shown to contribute to regeneration and repair of damaged tissues by differentiating into stromal cell types or releasing vesicles and soluble factors supporting the healing processes. However, there are no adequate reports about their roles during SG damage and regeneration so far. Using an irradiated SG mouse model, we performed certain immunostainings on tissue sections of submandibular glands at different time points after IR. Immunostaining for CD31 revealed that already one day after IR, vascular impairment was induced at the level of capillaries. In addition, the expression of CD44—a marker of acinar cells—diminished gradually after IR and, by 20 weeks, almost disappeared. In contrast, the number of CD34-positive cells significantly increased 4 weeks after IR and some of the CD34-positive cells were found to reside within the adventitia of arteries and veins. Laser confocal microscopic analyses revealed an accumulation of CD34-positive cells within the area of damaged capillaries where they were in close contact to the CD31-positive endothelial cells. At 4 weeks after IR, a fraction of the CD34-positive cells underwent differentiation into α-SMA-positive cells, which suggests that they may contribute to regeneration of smooth muscle cells and/or pericytes covering the small vessels from the outside. In conclusion, SG-resident CD34-positive cells represent a population of progenitors that could contribute to new vessel formation and/or remodeling of the pre-existing vessels after IR and thus, might be an important player during SG tissue healing.

Collagen IV, a promising serum biomarker for evaluating the prognosis of revascularization in a 2-kidney, 1-clip hypertensive rat model

OBJECTIVES

The goal of this study was to investigate the expression of serum collagen IV and its value for evaluating the prognosis of revascularization in a 2-kidney, 1-clip hypertensive rat model.

METHODS

A total of 40 Sprague-Dawley rats were randomly and evenly divided into a control group and 3-, 10- and 20-day (D) groups (namely, the ischaemic time for 3, 10 and 20 days, respectively). The systolic blood pressure and laboratory values such as serum creatinine and collagen IV levels were measured before and after clipping the renal artery. Histological Masson staining and immunohistochemical staining of collagen IV were conducted in a kidney specimen from each group to assess the severity of renal fibrosis and the level of collagen IV expression.

RESULTS

After clipping, systolic blood pressure in the 3D, 10D and 20D groups increased significantly from 108 ± 8 to 126 ± 7 and from 153 ± 8 to 157 ± 6 mmHg, respectively (10D vs 20D group, P = 0.224; between other groups, P < 0.001). The expression of serum creatinine in the 3D, 10D and 20D groups increased significantly from 35.39 ± 5.64 to 57.53 ± 7.05, 101.86 ± 8.94 and 119.76 ± 9.37 mmol/l, respectively (between each group: P < 0.001). Serum collagen IV levels in the 10D and 20D groups increased significantly from 38.5 ± 10.4 to 60.8 ± 15.0 and 87.3 ± 11.5 ng/ml, respectively (control vs 3D group, P = 0.718; between other groups, P < 0.001). The Masson staining indicated that sclerotic changes in the glomeruli of the 10D and 20D groups significantly increased from 2.20 ± 1.03 to 15.20 ± 5.03 and 28.20 ± 7.07%, respectively (control vs 3D group, P = 0.175; between other groups, P < 0.001). The grade of tubulointerstitial damage in the 3D, 10D and 20D groups increased significantly from 0.30 ± 0.48 to 1.90 ± 0.74, 1.80 ± 0.79 and 3.20 ± 0.79, respectively (3D vs 10D group, P = 0.755; between other groups, P < 0.001). The semi-quantification from immunohistochemical staining indicated that the percentage of collagen IV positive areas in the 3D, 10D and 20D groups increased significantly from 3.50 ± 1.58 to 8.60 ± 2.11, 16.60 ± 8.55 and 23.10 ± 6.15, respectively (control vs 3D group, P = 0.043; 3D vs 10D group, P = 0.002; 10D vs 20D group, P = 0.011; between other groups, P < 0.001). The area under the curve of the receiver operating characteristic curve was 0.783 (P = 0.008; 95% confidence interval 0.634-0.932). There were positive associations of serum collagen IV levels with systolic blood pressure, serum creatinine and collagen IV quantification in kidney with correlation coefficients of 0.665, 0.775 and 0.628, respectively (P < 0.001).

CONCLUSIONS

As the clear ischaemia time-response relationship identified in our study indicates, the increase in serum collagen IV levels may be a satisfactory biomarker to indicate a poor prognosis of renal artery revascularization in a 2-kidney, 1-clip hypertensive rat model. However, it is perhaps not a good early biomarker for the early detection of renovascular hypertension.

IL-6 Contributes to the TGF-β1-Mediated Epithelial to Mesenchymal Transition in Human Salivary Gland Epithelial Cells

To determine the role of IL-6 in bringing about the EMT, in SGEC obtained from healthy subjects. Human salivary gland (SGs) epithelial cells (SGEC) from primary Sjögren's syndrome (pSS) are able to synthesize interleukin (IL)-6, which is a critical mediator of the SGs modifications in response to chronic inflammation. Recently, a hypothetical link between epithelial-mesenchymal transition (EMT)-dependent salivary gland fibrosis and chronic inflammatory conditions has been suggested for pSS; the present study was conducted to evaluate this link. Primary cultures of human SGEC from salivary mucoceles were stimulated with increasing concentrations of IL-6 for 24-72 h. Microscopy, RT-PCR, Real-time PCR, immunoblotting and flow cytometry were used to detect morphological changes, mRNA and protein expression of the EMT markers E-Cadherin, Vimentin and Collagen type I following IL-6 stimulation. The data collected demonstrate that IL-6 can induce SGEC to undergo a morphological and phenotypical transition to a mesenchymal phenotype, in a dose-dependent manner. Decreased mRNA levels of E-Cadherin accompanied by higher mRNA levels of Vimentin and Collagen type I were observed in the IL-6-treated cells compared to control cells (all p < 0.05). This was confirmed at the protein level, demonstrating the decreased E-Cadherin expression, while Vimentin and Collagen type I expression was increased in IL-6-treated SGEC compared to controls (all p < 0.05). The results obtained corroborate the hypothesis that dysregulated cytokines IL-6 may contribute to the EMT-dependent fibrosis, offering a more complete understanding of the role of the EMT during SGs fibrosis in pSS.

miR‑155‑5p downregulation inhibits epithelial‑to‑mesenchymal transition by targeting SIRT1 in human nasal epithelial cells

Epithelial-to-mesenchymal transition (EMT) in nasal epithelial cells is involved with tissue remodeling of nasal polyps. The present study investigated the molecular mechanisms through which miR-155-5p regulated EMT in chronic rhinosinusitis (CRS). Patients were divided into the following groups: CRSsNP, CRS without nasal polyposis group, CRSwNP, CRS with nasal polyposis and controls. The expression of transforming growth factor (TGF)-β1, EMT markers, sirtuin 1 (SIRT1) and miR-155-5p were determined by western blotting and reverse transcription-quantitative PCR. Cell morphology following TGF-β1 treatment in the presence of miR-155-5p inhibitors or controls was observed under a microscope. Target genes and potential binding sites between miR-155-5p and SIRT1 were predicted by TargetScan and confirmed using dual-luciferase reporter assay. In patients with CRS, the expression levels of E-cadherin were downregulated and the expression levels of TGF-β1, mesenchymal markers and miR-155-5p were upregulated. Additionally, these changes in expression levels were reduced or increased to a greater extent in the CRSwNP group compared with the CRSsNP group. Furthermore, TGF-β1 expression promoted EMT in human nasal epithelial cells (HNEpCs) and upregulated miR-155-5p expression. These effects were reversed by miR-155-5p inhibitors. Additionally, SIRT1 was predicted as a target gene of miR-155-5p. Downregulation of miR-155-5p upregulated epithelial marker expression and downregulated mesenchymal marker expression by regulating SIRT1. Therefore, the downregulation of miR-155-5p inhibited EMT in HNEpCs by targeting SIRT1.

Antiepithelial-Mesenchymal Transition of Herbal Active Substance in Tumor Cells via Different Signaling

Epithelial-mesenchymal transition (EMT) is a biological process through which epithelial cells differentiate into mesenchymal cells. EMT plays an important role in embryonic development and wound healing; however, EMT also contributes to some pathological processes, such as tumor metastasis and fibrosis. EMT mechanisms, including gene mutation and transcription factor regulation, are complicated and not yet well understood. In this review, we introduce some herbal active substances that exert antitumor activity through inhibiting EMT that is induced by hypoxia, high blood glucose level, lipopolysaccharide, or other factors.

Thymic stromal lymphopoietin induced early stage of epithelial-mesenchymal transition in human bronchial epithelial cells through upregulation of transforming growth factor beta 1

Purpose: Epithelial-mesenchymal transition (EMT) involved in asthmatic airway remodeling. Thymic stromal lymphopoietin (TSLP), an epithelial-derived cytokine, was a key component in airway immunological response in asthma. But the role of TSLP in the EMT process was unknown. We aimed to access whether TSLP could induce EMT in airway epithelia and its potential mechanism. Materials and Methods: Human bronchial epithelial (HBE) cells were incubated with TSLP or transforming growth factor beta 1 (TGF-β1) or both. SB431542 was used to block TGF-β1 signal while TSLP siRNA was used to performed TSLP knockdown. Changes in E-cadherin, vimentin, collagen I and fibronectin level were measured by real-time PCR, western blot and immunofluorescence staining. Expressions of TGF-β after TSLP administration were measured by real-time PCR, western blot and ELISA. Results: TSLP induced changes of EMT relevant markers alone and promoted TGF-β1-induced EMT in HBEs. Intracellular and extracellular expression of TGF-β1 were upregulated by TSLP. SB431542 blocked changes of EMT relevant markers induced by TSLP. Knockdown of TSLP not only reduced TSLP and TGF-β1 expression but also inhibited changes of EMT relevant markers induced by TGF-β1 in HBEs. Conclusions: TSLP could induce early stage of EMT in airway epithelial cells through upregulation of TGF-β1. This effect may act as a targeting point for suppression of asthma.

Multifaceted Mechanisms of Areca Nuts in Oral Carcinogenesis: the Molecular Pathology from Precancerous Condition to Malignant Transformation

Oral cancer is one of the most frequent malignant diseases worldwide, and areca nut is a primary carcinogen causing this cancer in Southeast Asia. It has been widely reported that areca nut induced several cytotoxic effects in oral cells, including ROS generation, inflammation, tissue hypoxia, DNA damage, and cell invasion. Recently, through chronic exposure model, more extensive pathological effects due to areca nut have been found. These include the induction of autophagy, promotion of epithelial- mesenchymal transition, and facilitation of cancer stemness conversion. Clinical findings support these adverse effects. Oral submucosal fibrosis, a premalignant condition, is prevalent in the area with habitual chewing of areca nuts. Consistently, oral cancer patients with habitual chewing areca nut exhibit more aggressive phenotypes, including resistance to chemo-radiotherapy. In this review, we comprehensively discuss and concisely summarize the up-to-date molecular and cellular mechanisms by which areca nuts contribute to malignant transformation. This review may provide critical information regarding clinical applications in risk assessment, disease prevention, diagnosis, and personalized therapeutics for areca nut-induced oral malignancy.

MiR-145 inhibits EGF-induced epithelial-to-mesenchymal transition via targeting Smad2 in human glioblastoma

Background/Aims: MiR-145 and Smad2 have been widely reported in the development and progression of human malignancies. In the present study, we investigated the correlation between miR-145 and Smad2 in human glioblastoma multiforme (GBM).

Methods: The epithelial–mesenchymal transition (EMT) biomarkers and Smad2 were assessed by Western blot. The silencing of Smad2 was conducted by transfection of Smad2 siRNAs. The cell migration and invasion were evaluated using Transwell assays, respectively. The dual luciferase reporter assay was performed to identify whether Smad2 is a direct target of miR-145.

Results: The epidermal growth factor (EGF) activated the phosphorylation of Smad2 in U87 and U251 cells in a time- and dose-dependent manner. However, treatment with silencing of Smad2 or overexpression of miR-145 significantly inhibited the expressions of total Smad2, N-cadherin, Vimentin and matrix metallopeptidase 9, but induced the expression of E-cadherin. In addition, silencing of Smad2 or overexpression of miR-145 also inhibited the migration and invasion of U87 and U251 cells. Mechanistically, Smad2 was confirmed to be a target gene of miR-145 by bioinformatics analysis and luciferase reporter assay. Restored Smad2 expression also reversed miR-145-induced inhibition of EMT in U87 and U251 cells.

Conclusion: MiR-145 inhibits EGF-induced EMT via targeting Smad2 in human GBM. Therefore, miR-145 may be a promising biomarker and therapeutic target for GBM patients.

Cathepsin B Is Upregulated and Mediates ECM Degradation in Colon Adenocarcinoma HT29 Cells Overexpressing Snail

During tumor development and ongoing metastasis the acquisition of mesenchymal cell traits by epithelial carcinoma cells is achieved through a programmed phenotypic shift called the epithelial-to-mesenchymal transition, EMT. EMT contributes to increased cancer cell motility and invasiveness mainly through invadosomes, the adhesion structures that accompany the mesenchymal migration. The invadosomes and their associated proteases restrict protease activity to areas of the cell in direct contact with the ECM, thus precisely controlling cell invasion. Our data prove that Snail-overexpressing HT-29 cells that imitate the phenotype of colon cancer cells in the early stage of the EMT showed an increase in the expression and pericellular activity of cathepsin B. It appears that the pericellular localization of cathepsin B, also observed in colon and rectum adenocarcinoma tissue samples, plays a key role in its function.

The TGF-β1 Signaling Pathway as an Attractive Target in the Fibrosis Pathogenesis of Sjögren's Syndrome

Transforming growth factor β1 (TGF-β1) plays a crucial role in the induction of fibrosis, often associated with chronic phases of inflammatory diseases contributing to marked fibrotic changes that compromise normal organ function. The TGF-β1 signal exerts its biological effects via the TGF-β/SMAD/Snail signaling pathway, playing an important pathogenic role in several fibrotic diseases. It has as yet been poorly investigated in the chronic autoimmune disease Sjögren's syndrome (SS). Here, we firstly tested, by immunohistochemistry, whether the TGF-β1/SMAD/Snail signaling pathway is triggered in human pSS salivary glands (SGs). Next, healthy salivary gland epithelial cell (SGEC) cultures derived from healthy donors were exposed to TGF-β1 treatment, and the relative gene and protein levels of SMAD2/3/4, Snail, E-cadherin, vimentin, and collagen type I were compared by semiquantitative RT-PCR, quantitative real-time PCR, and Western blot analysis. We observed, both at gene and protein levels, higher expression of SMAD2, 3, and 4 and Snail in the SGEC exposed by TGF-β1 compared to untreated healthy SGEC. Additionally, in TGF-β1-treated samples, we found a significant reduction in the epithelial phenotype marker E-cadherin and an increase in the mesenchymal phenotype markers vimentin and collagen type I compared to those in untreated SGEC, indicating that TGF-β1 induces the EMT via the TGF-β1/SMAD/Snail signaling pathway. Therefore, by using the specific TGF-β receptor 1 inhibitor SB-431542 in healthy SGEC treated with TGF-β1, we showed a significant reduction of the fibrosis markers vimentin and collagen type I while the epithelial marker E-cadherin returns to levels similar to untreated healthy SGEC. These data demonstrate that TGF-β1 is an important key factor in the transition phase from SG chronic inflammation to fibrotic disease. Characteristic changes in the morphology and function of TGF-β1-treated healthy SGEC further confirm that TGF-β1 plays a significant role in EMT-dependent fibrosis.