Salivary Cells Research Articles

Increased cell killing effect in neutron capture enhanced proton beam therapy

AbstractThermal neutrons generated in the body during proton beam therapy (PBT) can be used to cause boron neutron capture reactions and have recently been proposed as neutron capture enhanced PBT (NCEPBT). However, the cell killing effect of NCEPBT remains underexplored. Here, we show an increase in the cell killing effect of NCEPBT. Using Monte Carlo simulations, we showed that neutrons generated by proton beam irradiation are uniformly spread on tissue culture plates. Human salivary gland tumor cell line (HSG), human osteosarcoma cell line (MG63), human tongue squamous cell carcinoma cell line (SAS), and human malignant melanoma cell line (G-361) were irradiated with X-rays, proton beams, and proton beams with 10B-enriched boronophenylalanine (boron concentration of 20 and 80 ppm). The relative biological effectiveness (RBE) values of proton beams alone, proton beams with 20 ppm boron, and proton beams with 80 ppm boron for HSG, MG63, SAS, and G-361 were 1.02, 1.07, and 1.23; 1.01, 1.08, and 1.44; 1.05, 1.09, and 1.46; and 1.04, 1.13, and 1.63, respectively. NCEPBT with high boron concentration showed high RBE and a high sensitizing effect. Our results confirm an increase in the cell killing effect of NCEPBT, should aid in its clinical use, and warrant its further investigation.

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

BackgroundSecretion 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.MethodsRat 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.ResultsElevated 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.ConclusionOur 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.

Anti-EGFR antibody immunotoxins improve cytotoxic effects in the salivary gland cancer A253 cell line

Anti-EGFR antibody immunotoxins improve cytotoxic effects in the salivary gland cancer A253 cell line

The regulating role of galectin-9 in immune cell populations.

Galectin-9 (gal-9) is a protein that belongs to the galectin family. Gal-9 is expressed in cells of the innate and adaptive immune system, including lymphocytes, dendritic cells, giant salivary cells, eosinophils and T cells, etc. In different immune cells, the role of gal-9 is different. Gal-9 can induce the proliferation and activation of immune cells, and also promote the apoptosis of immune cells. This effect of gal-9 affects the occurrence and development of a variety of immune-related diseases, such as the invasion of pathogenic microorganisms, immune escape of tumor cells, and inflammatory response. Thus, understanding the biological roles of gal-9 in innate and adaptive immunity may be essential for autoimmune diseases treatment and diagnosis to improve patient quality of life. In this review, we aim to summarize current research on the regulatory roles of gal-9 in human immune system and potential inducers and inhibitors of gal-9, which may provide new strategies for immune diseases therapies.

Pancreatic Differentiation of Oral Minor Salivary Gland Stem Cells.

Stem cells from various sources including major salivary glands have been used to establish pancreatic differentiation in an attempt to provide new treatment options for patients with diabetes mellitus. In contrast, the potential of using the more easily accessible intraoral minor salivary glands has not been evaluated so far. Salivary stem cells were isolated from normal labial minor salivary glands that were removed during the excision of a mucocele and were attempted to differentiate into pancreatic cell lines using a culture medium enriched with activin A, retinoic acid and GLP-1.Real time RT-PCR was used to evaluate the expression of the genes of pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx. Complementary, 22 labial minor salivary gland paraffin-embedded specimens were examined using immunohistochemistry for the presence of the relevant gene products of the pancreatic transcription factors Arx, MafA, Ptf1a and Pdx1. The differentiated salivary stem cells(cells of passage 3) expressed the genes of the pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx even on the first day of the experiment while immunohistochemistry also confirmed the presence of the protein products of Arx, MafA, Ptf1a as well as Pdx1[> 50% of the specimens for Arx(5/8) and MafA(7/8), < 50% for Ptf1a(5/11) and Pdx1(5/11)] in ducts, mesenchymal connective tissue and acinar cells. Labial minor salivary glands may share gene and protein characteristics with pancreas suggesting a possible usefulness for pancreatic regeneration or substitution in cases of deficiency.

The impact of alternate-day fasting on the salivary gland stem cell compartments in non-obese diabetic mice with newly established Sjögren's syndrome.

Intermittent fasting exerts a profound beneficial influence on a spectrum of diseases through various mechanisms including regulation of immune responses, elimination of senescent- and pathogenic cells and improvement of stem cell-based tissue regeneration in a disease- and tissue-dependent manner. Our previous study demonstrated that alternate-day fasting (ADF) led to alleviation of xerostomia and sialadenitis in non-obese diabetic (NOD) mice, a well-defined model of Sjögren's syndrome (SS). This present study delved into the previously unexplored impacts of ADF in this disease setting and revealed that ADF increases the proportion of salivary gland stem cells (SGSCs), defined as the EpCAMhi cell population among the lineage marker negative submandibular gland (SMG) cells. Furthermore, ADF downregulated the expression of p16INK4a, a cellular senescence marker, which was concomitant with increased apoptosis and decreased expression and activity of NLRP3 inflammasomes in the SMGs, particularly in the SGSC-residing ductal compartments. RNA-sequencing analysis of purified SGSCs from NOD mice revealed that the significantly downregulated genes by ADF were mainly associated with sugar metabolism, amino acid biosynthetic process and MAPK signaling pathway, whereas the significantly upregulated genes related to fatty acid metabolic processes, among others. Collectively, these findings indicate that ADF increases the SGSC proportion, accompanied by a modulation of the SGSC property and a switch from sugar- to fatty acid-based metabolism. These findings lay the foundation for further investigation into the functionality of SGSCs influenced by ADF and shed light on the cellular and molecular mechanisms by which ADF exerts beneficial actions on salivary gland restoration in SS.

Managing malignant sublingual gland tumors: a single institution experience with 23 patients

BackgroundDue to the relative rarity of malignant sublingual gland tumors, diagnosing and treating them clinically pose challenges. Hence, there’s a need to explore the pathological types, characteristics, treatment methods, and prognosis of primary malignant tumors of the sublingual gland to improve our understanding and management of these rare yet highly malignant conditions.MethodsThis study reviewed cases of primary malignant sublingual gland tumors, analyzing their characteristics. The treatment methods included surgical excision, with additional radiotherapy, or brachytherapy for advanced stages or positive surgical margins. The study also summarized different treatment approaches, including lymph node dissection and soft tissue reconstruction using free flaps such as the anterolateral thigh flap and forearm flap.ResultsWe have gathered 23 cases of sublingual gland malignancies treated at the Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, from January 2013 to May 2024. The most common pathological types were adenoid cystic carcinoma and mucoepidermoid carcinoma, with rare cases of mucosa-associated lymphoid tissue (MALT) lymphoma and nonspecific salivary gland clear cell carcinoma. Early diagnosis and surgical intervention were crucial for a favorable prognosis. Marginal mandibulectomy was necessary for cases involving the mandible. Patients with positive preoperative lymph node detection required cervical lymph node dissection. Extensive tissue defects in the floor of the mouth were effectively reconstructed with free flaps to prevent oral-mandibular fistula.ConclusionSurgical excision remains the preferred treatment for malignant sublingual gland tumors. Early diagnosis and comprehensive surgical management are essential for improving prognosis. The study’s limitations include a small sample size and short follow-up duration, necessitating further research with larger clinical samples to confirm these findings.

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.

Pseudonormal Morphology of Salivary Gland Adenoid Cystic Carcinoma Cells Subverts the Antitumor Reactivity of Immune Cells: A Tumour-Cell-Based Initiation of Immune Evasion.

Salivary gland adenoid cystic carcinoma (ACC), mucoepidermoid carcinoma (MEC) and oral squamous cell carcinoma (OSCC) occurs within the head and neck region. So far immune check point inhibitors failed in ACC. Gipie (CCDC88B) is a microtubule linker protein that activates immune cells. Gipie expressions found in head and neck cancer cells. We hypothesised that the presence of Gipie diminishes anti-tumour reactivity of immune cells towards head and neck cancer. To determine the effect of Gipie in oral and salivary gland cancer cells, Gipie was silenced in cancer cells in cancer-immune cells co-culture models and we performed 3D Z series confocal imaging, annexin V and immune activation flow cytometry, proteome profiler and discovery phase proteomics. ACC cells morphed into pseudonormal morphology in immune co-culture models. Silencing Gipie in ACC cells showed significant increase of apoptotic cells and activated natural killer cells, and lowering of regulatory T cells. Other salivary and oral cancer cells showed negligible effect of Gipie. Proteome profiler and proteomics assay confirmed Gipie affecting proliferation mechanism and immune activated proteins in ACC immune co-culture models. Overall, we conclude that the presence of Gipie has a confounding role during the ACC-immune cell interaction.

Syndecan-1 Plays a Role in the Pathogenesis of Sjögren's Disease by Inducing B-Cell Chemotaxis through CXCL13-Heparan Sulfate Interaction.

In Sjögren's disease (SjD), the salivary glandular epithelial cells can induce the chemotaxis of B cells by secreting B-cell chemokines such as C-X-C motif chemokine ligand 13 (CXCL13). Syndecan-1 (SDC-1) is a major transmembrane heparan sulfate proteoglycan (HSPG) predominantly expressed on epithelial cells that binds to and regulates heparan sulfate (HS)-binding molecules, including chemokines. We aimed to determine whether SDC-1 plays a role in the pathogenesis of SjD by acting on the binding of HS to B-cell chemokines. To assess changes in glandular inflammation and SDC-1 concentrations in the submandibular gland (SMG) and blood, female NOD/ShiLtJ and sex- and age-matched C57BL/10 mice were used. In the SMG of NOD/ShiLtJ mice, inflammatory responses were identified at 8 weeks of age, but increased SDC-1 concentrations in the SMG and blood were observed at 6 weeks of age, when inflammation had not yet started. As the inflammation of the SMG worsened, the SDC-1 concentrations in the SMG and blood increased. The expression of the CXCL13 and its receptor C-X-C chemokine receptor type 5 (CXCR5) began to increase in the SMG at 6 weeks of age and continued until 12 weeks of age. Immunofluorescence staining in SMG tissue and normal murine mammary gland cells confirmed the co-localization of SDC-1 and CXCL13, and SDC-1 formed a complex with CXCL13 in an immunoprecipitation assay. Furthermore, NOD/ShiLtJ mice were treated with 5 mg/kg HS intraperitoneally thrice per week for 6-10 weeks of age, and the therapeutic effects in the SMG were assessed at the end of 10 weeks of age. NOD/ShiLtJ mice treated with HS showed attenuated salivary gland inflammation with reduced B-cell infiltration, germinal center formation and CXCR5 expression. These findings suggest that SDC-1 plays a pivotal role in the pathogenesis of SjD by binding to CXCL13 through the HS chain.

Salivary gland organoid transplantation as a therapeutic option for radiation-induced xerostomia

BackgroundXerostomia is a pathological condition characterized by decreased salivation due to salivary gland dysfunction and is frequently attributed to irreversible damage as a side effect of radiation therapy. Stem cell–derived organoid therapy has garnered attention as a promising avenue for resolving this issue. However, Matrigel, a hydrogel commonly used in organoid culture, is considered inappropriate for clinical use due to its undefined composition and immunogenicity. In this study, we aimed to develop a method for culturing collagen-based human salivary gland organoids (hSGOs) suitable for clinical applications and evaluated their therapeutic effectiveness.MethodsHuman salivary gland stem cells were isolated from the salivary gland tissues and cultured in both Matrigel and collagen. We compared the gene and protein expression patterns of salivary gland–specific markers and measured amylase activity in the two types of hSGOs. To evaluate the therapeutic effects, we performed xenogeneic and allogeneic transplantation using human and mouse salivary gland organoids (hSGOs and mSGOs), respectively, in a mouse model of radiation-induced xerostomia.ResultshSGOs cultured in Matrigel exhibited self-renewal capacity and differentiated into acinar and ductal cell lineages. In collagen, they maintained a comparable self-renewal ability and more closely replicated the characteristics of salivary gland tissue following differentiation. Upon xenotransplantation of collagen-based hSGOs, we observed engraftment, which was verified by detecting human-specific nucleoli and E-cadherin expression. The expression of mucins, especially MUC5B, within the transplanted hSGOs suggested a potential improvement in the salivary composition. Moreover, the allograft procedure using mSGOs led to increased salivation, validating the efficacy of our approach.ConclusionsThis study showed that collagen-based hSGOs can be used appropriately in clinical settings and demonstrated the effectiveness of an allograft procedure. Our research has laid the groundwork for the future application of collagen-based hSGOs in allogeneic clinical trials.

A TNIP1-driven systemic autoimmune disorder with elevated IgG4

Whole-exome sequencing of two unrelated kindreds with systemic autoimmune disease featuring antinuclear antibodies with IgG4 elevation uncovered an identical ultrarare heterozygous TNIP1Q333P variant segregating with disease. Mice with the orthologous Q346P variant developed antinuclear autoantibodies, salivary gland inflammation, elevated IgG2c, spontaneous germinal centers and expansion of age-associated B cells, plasma cells and follicular and extrafollicular helper T cells. B cell phenotypes were cell-autonomous and rescued by ablation of Toll-like receptor 7 (TLR7) or MyD88. The variant increased interferon-β without altering nuclear factor kappa-light-chain-enhancer of activated B cells signaling, and impaired MyD88 and IRAK1 recruitment to autophagosomes. Additionally, the Q333P variant impaired TNIP1 localization to damaged mitochondria and mitophagosome formation. Damaged mitochondria were abundant in the salivary epithelial cells of Tnip1Q346P mice. These findings suggest that TNIP1-mediated autoimmunity may be a consequence of increased TLR7 signaling due to impaired recruitment of downstream signaling molecules and damaged mitochondria to autophagosomes and may thus respond to TLR7-targeted therapeutics.

First Description of Mycoplasma agalactiae Anatomical Localization in Naturally Infected Hard Ticks (Rhipicephalus bursa).

Mycoplasma agalactiae (Ma) is considered the primary causative agent of contagious agalactia (CA) in sheep and goats, which causes severe losses to the small ruminant dairy industry. As early as 1816, it was thought that environmental factors played a role in pathogen maintenance in endemic areas. Specifically, recent studies hypothesized a vector role for arthropods in the epidemiology of disease. The aim of this study was to investigate the presence and anatomical localization of Ma in naturally infected Riphicephalus bursa ticks to better evaluate tick-pathogen interactions. Salivary glands and ovaries of confirmed Ma-positive R. bursa were analyzed to look for the Ma antigen using immunohistochemistry (IHC). IHC showed strong positivity to Ma in the cytoplasm of salivary cells as well as in cells from the ovary. Our work demonstrated for the first time the crossing of the tick midgut barrier by Ma and the subsequent infection of organs capable of spreading the infection, and this result represents an absolute novelty in disease-related knowledge. Our preliminary results provide conclusive evidence of the potential vector role represented by hard ticks in the epidemiology of CA. Further field and laboratory investigations are necessary to confirm the tick role in the transmission of clinical CA.

DUSP1 and SOX2 expression determine squamous cell carcinoma of the salivary gland progression

Salivary gland squamous cell carcinomas (SG-SCCs) constitute a rare type of head and neck cancer which is linked to poor prognosis. Due to their low frequency, the molecular mechanisms responsible for their aggressiveness are poorly understood. In this work we studied the role of the phosphatase DUSP1, a negative regulator of MAPK activity, in controlling SG-SCC progression. We generated DUSP1 KO clones in A253 human cells. These clones showed a reduced ability to grow in 2D, self-renew in ECM matrices and to form tumors in immunodeficient mice. This was caused by an overactivation of the stress and apoptosis kinase JNK1/2 in DUSP1−/+ clones. Interestingly, RNAseq analysis revealed that the expression of SOX2, a well-known self-renewal gene was decreased at the mRNA and protein levels in DUSP1−/+ cells. Unexpectedly, CRISPR-KO of SOX2 did not recapitulate DUSP1−/+ phenotype, and SOX2-null cells had an enhanced ability to self-renew and to form tumors in mice. Gene expression analysis demonstrated that SOX2-null cells have a decreased squamous differentiation profile -losing TP63 expression- and an increased migratory phenotype, with an enhanced epithelial to mesenchymal transition signature. In summary, our data indicates that DUSP1 and SOX2 have opposite functions in SG-SCC, being DUSP1 necessary for tumor growth and SOX2 dispensable showing a tumor suppressor function. Our data suggest that the combined expression of SOX2 and DUSP1 could be a useful biomarker to predict progression in patients with SG-SCCs.

Unique Cohorts of Salivary Gland Cancer Cells as an in-vitro Model of Circulating Tumor Cells.

The characterization of circulating tumor cells (CTC) and circulating tumor microemboli (CTM) has emerged as both a challenge to the standard view of metastasis, and as a valuable means for understanding genotypic and phenotypic variability shown even within the same cancer type. However, in the case of salivary gland neoplasms, limited data are available for the role that CTCs and CTMs play in metastasis and secondary tumor formation.ru.AQ1 In response to this, we propose that similarities between in vitro clusters of cultured salivary gland cancer cells may act as a surrogate model for in vivo CTCs and CTMs isolated from patients. Using techniques in immunofluorescence, immunoblotting, and 2-dimensional migration, we isolated and characterized a group of cohort cells from a commercially available cell line (HTB-41). Results: Here, cells exhibited a hybrid phenotype with simultaneous expression of both epithelial and mesenchymal markers (E-cadherin, vimentin, and α-SMA). Cohort cells also exhibited increased migration in comparison to parental cells. Data suggest that these isolated cell clusters may fucntion as a potential in vitro model of CTCs and CTMs.

SARS-CoV-2 Infection of Salivary Glands Compromises Oral Antifungal Innate Immunity and Predisposes to Oral Candidiasis.

Saliva contains antimicrobial peptides considered integral components of host innate immunity, and crucial for protection against colonizing microbial species. Most notable is histatin-5 which is exclusively produced in salivary glands with uniquely potent antifungal activity against the opportunistic pathogen Candida albicans. Recently, SARS-CoV-2 was shown to replicate in salivary gland acinar cells eliciting local immune cell activation. In this study, we performed mechanistic and clinical studies to investigate the implications of SARS-CoV-2 infection on salivary histatin-5 production and Candida colonization. Bulk RNA-sequencing of parotid salivary glands from COVID-19 autopsies demonstrated statistically significant decreased expression of histatin genes. In situ hybridization, coupled with immunofluorescence for co-localization of SARS-CoV-2 spike and histatin in salivary gland cells, showed that histatin was absent or minimally present in acinar cells with replicating viruses. To investigate the clinical implications of these findings, salivary histatin-5 levels and oral Candida burden in saliva samples from three independent cohorts of mild and severe COVID-19 patients and matched healthy controls were evaluated. Results revealed significantly reduced histatin-5 in SARS-CoV-2 infected subjects, concomitant with enhanced prevalence of C. albicans. Analysis of prospectively recovered samples indicated that the decrease in histatin-5 is likely reversible in mild-moderate disease as concentrations tended to increase during the post-acute phase. Importantly, salivary cytokine profiling demonstrated correlations between activation of the Th17 inflammatory pathway, changes in histatin-5 concentrations, and subsequent clearance of C. albicans in a heavily colonized subject. The importance of salivary histatin-5 in controlling the proliferation of C. albicans was demonstrated using an ex vivo assay where C. albicans was able to proliferate in COVID-19 saliva with low histatin-5, but not with high histatin-5. Taken together, the findings from this study provide direct evidence implicating SARS-CoV-2 infection of salivary glands with compromised oral innate immunity, and potential predisposition to oral candidiasis.

Establishment and characterization of cMYB-expressing human salivary adenoid cystic carcinoma cell lines (UM-HACC-14, UM-HACC-6) and matching patient-derived xenograft model (UM-PDX-HACC-14)

Limited availability of authentic human adenoid cystic carcinoma (ACC) cell lines has hindered progress in understanding mechanisms underpinning the biology of this disease and the development of safe and effective therapies. Surgical human ACC specimens (UM-HACC-6, UM-HACC-14) were dissociated into single cell suspensions and cultured in fibronectin-coated flasks. Alternatively, tumor fragments were transplanted subcutaneously into female immunodeficient (SCID) mice to establish patient-derived xenograft tumors (PDX; UM-PDX-HACC-14). Both ACC cell lines showed continuous growth in monolayers for over 100 passages. Total RNA-Seq, RT-PCR, and FISH analysis revealed that both are MYB-NFIB fusion negative. Western blots revealed passage-dependent expression of E-Cadherin, PCNA, p63, phospho-c-MYB, and NFIB. Both, UM-HACC-14 and UM-HACC-6 cells exhibited tumorigenic potential when injected orthotopically into mouse submandibular glands. UM-HACC-14, patient-matching UM-PDX-HACC-14, and the UM-HACC-6 cell line are new, authenticated preclinical models of ACC that are well suited for mechanistic and developmental therapeutics studies.

Salivary duct carcinoma with squamous differentiation: histomorphological and immunophenotypical analysis of six cases.

Salivary duct carcinoma (SDC) is an aggressive salivary malignancy with multiple morphological subtypes. Primary salivary squamous cell carcinoma (SCC) requires exclusion of high-grade salivary malignancies and metastatic disease and is considered exceptionally rare. We report six cases of SDC with resemblance to SCC on account of variable, but often extensive, squamous differentiation. A retrospective review (2009-2023) at two institutions of SDC with histological and immunophenotypical evidence of squamous differentiation identified six cases. Medical charts and available glass slides were reviewed. There were five males and one female with a median age of 63 years, with tumours involving the parotid (five of six) and submandibular (one of six) glands. All six tumours showed a conventional SDC component comprising < 5-90% of viable tumour. Squamous differentiation comprised 10-95%+ (> 75% in three of six cases) of total viable tumour, and demonstrated CK5/6, p63 and/or p40 immunoexpression in all cases. A sarcomatoid component, comprising 10-60% of viable tumour, was present in three of six (50%) cases. All tumours were androgen receptor (AR)-positive, but only two of six (33.3%) retained AR immunoreactivity in the squamous component. Metastatic SDC to regional lymph nodes exhibited exclusive squamous differentiation in two of six (33.3%) cases. Squamous differentiation, histologically and immunophenotypically, can be extensive in SDC. AR expression may be lost in the squamous component and metastases may demonstrate only squamous differentiation. These findings cast further doubt on the existence of primary salivary SCC. SDC should be considered whenever encountering a carcinoma with squamous differentiation in major salivary glands or within cervical lymph nodes in the setting of a salivary mass.

Deleting Mitochondrial Superoxide Dismutase 2 in Salivary Gland Ductal Epithelial Cells Recapitulates Non-Sjögren's Sicca Syndrome.

Elevated oxidative stress can play a pivotal role in autoimmune diseases by exacerbating inflammatory responses and tissue damage. In Sjögren's disease (SjD), the contribution of oxidative stress in the disease pathogenesis remains unclear. To address this question, we created mice with a tamoxifen-inducible conditional knockout (KO) of a critical antioxidant enzyme, superoxide dismutase 2 (Sod2), in the salivary glands (i-sg-Sod2 KO mice). Following tamoxifen treatment, Sod2 deletion occurred primarily in the ductal epithelium, and the salivary glands showed a significant downregulation of Sod2 expression. At twelve weeks post-treatment, salivary glands from the i-sg-Sod2 KO mice exhibited increased 3-Nitrotyrosine staining. Bulk RNA-seq revealed alterations in gene expression pathways related to ribosome biogenesis, mitochondrial function, and oxidative phosphorylation. Significant changes were noted in genes characteristic of salivary gland ionocytes. The i-sg-Sod2 KO mice developed reversible glandular hypofunction. However, this functional loss was not accompanied by glandular lymphocytic foci or circulating anti-nuclear antibodies. These data demonstrate that although localized oxidative stress in salivary gland ductal cells was insufficient for SjD development, it induced glandular dysfunction. The i-sg-Sod2 KO mouse resembles patients classified as non-Sjögren's sicca and will be a valuable model for deciphering oxidative-stress-mediated glandular dysfunction and recovery mechanisms.

Interleukin-10 induces TNF-driven apoptosis and ROS production in salivary gland cancer cells

Treatment resistance after chemo-/immunotherapy occurs in patients with head and neck squamous cell cancers (HNSCs), including salivary gland cancers (SGCs). Interleukin-10 (IL-10), a cytokine with pro- and anti-cancer effects, has an unclear impact on HNSC/SGC cells. We show that HNSC patients exhibiting high expression of IL-10 and its receptor IL-10Rα experience have prolonged overall survival. Immunoreactive IL-10 was low in ductal cells of human SGC biopsies. Human (A253) and murine WR21-SGC cells expressed IL-10Rβ, but only A253 cells expressed IL-10 and IL-10Rα. The addition of recombinant IL-10 impaired SGC cell proliferation and induced apoptosis in vitro. N-acetylcysteine restored IL-10-induced reactive oxygen species (ROS) production but did not prevent IL-10-mediated viability loss. Mechanistically, recIL-10 delayed cell cycle progression from G0/G1 to the S phase with cyclin D downregulation and upregulation of NF-kB. IL-10 increased tumor necrosis factor-α (TNF-α) in A253 and WR21 and FasL in WR21 cells. Neutralizing antibodies against TNF-α and NF-kB inhibition restored SGC proliferation after IL-10 treatment, emphasizing the critical role of TNF-α and NF-kB in IL-10-mediated anti-tumor effects. These findings underscore the potential of IL-10 to impede SGC cell growth through apoptosis induction, unraveling potential therapeutic targets for intervention in salivary gland carcinomas.