Pathogenesis of sialadenosis: possible role of functionally deficient myoepithelial cells

Unusual Presentation of Primary Hyper-IgE-Related Salivary Gland Disease in a 13-Year-Old Male

Adenomas are common pathologies of the salivary glands that are often associated with the major salivary glands and occur in the fourth to sixth decades of life. They are seldom seen in the pediatric age group and rarely in the minor salivary glands. Autoimmune sialadenosis of the minor salivary glands is a new phenomenon that has seldom been reported in the literature, with as few as three cases. Histopathological examination of the excised specimen is the definitive diagnosis, and these lesions have to be differentiated from adenomas and low-grade malignancies of the minor salivary glands. Management strategies of these lesions are extremely variable, ranging from wait-and-watch principle to the use of immunosuppressants and excision of the gland. This case report discusses the etiopathogenesis of the autoimmune sialadenosis and the management strategies.

Management Options for Sialadenosis

Sialadenosis (sialosis) is a chronic, noninflammatory, nonneoplastic, bilateral, often painless enlargement of the salivary glands, most frequently affecting the parotid glands. Approximately 50% of cases are associated with an underlying disease process. The pathogenesis of sialadenosis is unknown but likely results from an autonomic neuropathy. The key to management is diagnosis and management of any poorly controlled underlying medical process.

Localized peripheral autonomous neuropathy and dysfunctional myoepithelial cells: A novel hypothesis for xerostomia in oral submucous fibrosis

Oral submucous fibrosis (OSMF) is a potentially malignant disorder of the oral cavity characterized by submucosal deposition of dense collagen bundles leading to limited mouth opening. Besides, patients also complain about the burning sensation in the oral cavity and xerostomia. These symptoms have a major impact on the functional and psychological domains of oral health-related quality of life. However, the pathogenesis of xerostomia in OSMF is not yet well established. In our routine histopathology practice, we observed fibrosis surrounding minor salivary glands, distended acini, obliteration of acinar lumen and loss of interstitial spaces. Based on these features, we hypothesized that fibrosis in OSMF drives localized peripheral autonomous neuropathy in minor salivary glands, which leads to dysfunctional myoepithelial cells. These dysfunctional myoepithelial cells will unable to contract and expel saliva out of the salivary secretary unit, thus leading to xerostomia. In the present paper, experiments are recommended to prove this hypothesis, which can be exploited in the future for the development of appropriate drugs.

Proliferative Activity of Myoepithelial Cells in Normal Salivary Glands and Adenoid Cystic Carcinomas Based on Double Immunohistochemical Labeling

Objective

To investigate the proliferative activity of myoepithelial cells (MEC) in normal salivary glands (NSG) and adenoid cystic carcinomas (ACC)) Study design. Twenty -three salivary gland specimens (13 ACC, 10 NSG) were studied using double immunohistochemical labeling for α smooth muscle actin (a-SMA) and proliferative cell nuclear antigen (PCNA)).

Results

There was a significant difference in PCNA reactivity in normal samples between myoepithelial cells of the parotid glands and of the submandibular glands, rates being higher in the latter. Neoplastic myoepithelial cells exhibited higher expression than neoplastic epithelial cells. In addition, myoepithelial cells of the cribriform type of ACC showed PCNA reactivity lower than those of the tubular type, whereas there was no statistically significant difference in epithelial cell rates. We could not identify myoepithelial cells in solid pattern due to α-SMA negativity; although high PCNA reactivity was evident.

Conclusion

These data suggest that the myoepithelial cell has a key role in ACC oncogenesis, more so than its epithelial cell counterparts. Moreover, the data provide a histopathological interpretation for aggressive clinical features of submandibular ACC, as the myoepithelial cells were less differentiated as compared to those of parotid glands.

Myoepithelial cell-driven acini contraction in response to oxytocin receptor stimulation is impaired in lacrimal glands of Sjögren's syndrome animal models

The purpose of the present studies was to investigate the impact of chronic inflammation of the lacrimal gland, as occurs in Sjögren’s syndrome, on the morphology and function of myoepithelial cells (MECs). In spite of the importance of MECs for lacrimal gland function, the effect of inflammation on MECs has not been well defined. We studied changes in MEC structure and function in two animal models of aqueous deficient dry eye, NOD and MRL/lpr mice. We found a statistically significant reduction in the size of MECs in diseased compared to control lacrimal glands. We also found that oxytocin receptor was highly expressed in MECs of mouse and human lacrimal glands and that its expression was strongly reduced in diseased glands. Furthermore, we found a significant decrease in the amount of two MEC contractile proteins, α-smooth muscle actin (SMA) and calponin. Finally, oxytocin-mediated contraction was impaired in lacrimal gland acini from diseased glands. We conclude that chronic inflammation of the lacrimal gland leads to a substantial thinning of MECs, down-regulation of contractile proteins and oxytocin receptor expression, and therefore impaired acini contraction. This is the first study highlighting the role of oxytocin mediated MEC contraction on lacrimal gland function.

Reduced myofilament component in primary Sjögren's syndrome salivary gland myoepithelial cells

Primary Sjögren's syndrome (pSS) is a solitary poorly understood autoimmune inflammatory disease by involvement of the salivary and lacrimal glands resulting in dry mouth and dry eyes. Myoepithelial cells (MECs) are cells knowing for its hybrid epithelial and mesenchymal phenotype that are important components of the salivary gland (SGs) structure aiding the expulsion of saliva from acinar lobules. In this study we investigate possible alteration in the myofilament component of MECs in SGs specimens obtained from pSS patients in comparison with healthy subjects, to evaluate MECs hypothetical involvement in the pathogenesis of pSS. The expression of alpha-smooth muscle actin (α-SMA) and p63, as MECs markers, was evaluated in bioptic specimens from pSS and healthy labial SGs through immunohistochemistry and immunofluorescence analyses; the distribution of MECs markers was quantified using Aperio ScanScope and ImageScope software to provide quantitative assessments of staining levels. Our observations demonstrated that p63 nuclear labeling in pSS MECs is preserved whereas α-SMA cytoplasmic staining is strongly and significantly reduced when compared with healthy SGs; the digital images analysis quantification of the expression of labeled α-SMA and p63 protein in the healthy and pSS MECs salivary tissues, led to results suggesting a loss of mechanical support for acini and ducts in pSS, correlated, probably, with the reduction of salivary flow that features one important aspect of pSS disease.

Bilateral Parotid Swelling in Polycystic Ovarian Syndrome

Polycystic ovarian syndrome (PCOS) is recognized by the presence of polycystic ovaries, irregular menstruation, and increased androgen levels. Many patients have insulin resistance or impaired glucose tolerance and an associated development of type 2 diabetes mellitus. A patient with PCOS is presented whose cosmetic concerns centered on the prolonged existence of substantial bilateral parotid swelling. The pathophysiology, diagnosis, and therapy of sialosis are discussed.

Salivary gland disorders

Patients with salivary gland disease present with certain objective and/or subjective signs. An accurate diagnosis for these patients requires a range of techniques that includes the organized integration of information derived from their history, clinical examination, imaging, serology, and histopathology. This article highlights the signs and symptoms of the salivary gland disorders seen in the Salivary Gland Center, and emphasizes the methodology used to achieve a definitive diagnosis and therapy.

Morphometrical study of minor salivary gland in xerostomic patients with altered lipid metabolism

OBJECTIVE

To evaluate the correlation between dyslipidemia in patients with oral dryness and the development of non-specific histopathological findings in their labial salivary gland biopsies.

METHODS

Thirty seven patients suffering from oral dryness (18 patients with dyslipidemia and 19 age-matched patients with normal lipid blood levels) underwent labial salivary gland biopsy. Total acinar area (TAA), acinar cell number, acinar lumen area (ALA), duct lumen area (DLA), area occupied by cells in acinus (AoCA), and area of one acinar cell (OAC) were calculated.

RESULTS

A significantly (P < 0.05) increased AoCA, OAC, and DLA in labial glands from patients with impaired lipid metabolism, compared to controls, were found.

CONCLUSION

A positive relationship between dyslipidemia and morphological changes in labial salivary glands was obtained.

A perspective of comparative salivary and breast pathology. Part I: microstructural aspects, adaptations and cellular events

This is the first part of a review comparing the pathology of salivary and mammary glands. Here, less obvious similarities and differences in functional histology and their influences on pathology are examined with emphasis on myoepithelial cells, stromal components, analogues of mucosa-associated lymphoid tissue, steroid receptors, and intraparenchymal cells of monocytic lineage. Particular cell phenotypes (oncocytic, apocrine, neuroendocrine and clear) are critically evaluated and responses to atrophy, infarction and fine-needle aspiration biopsy procedures are highlighted together with aspects of metaplasia, regeneration, ageing and microcalcification. Areas of controversy or uncertainty which may benefit from further investigations are also discussed.

Atrophy of myoepithelial cells in parotid glands of diabetic mice; detection using skeletal muscle actin, a novel marker

In mouse parotid glands, we found expression of skeletal muscle actin (actin-α1) protein and mRNA. We isolated myoepithelial cells from the mouse parotid glands and investigated their actin-α1 expression because smooth muscle actin (actin-α2) has been used as a marker for myoepithelial cells. We used actin-α1 expression to identify pathological changes in diabetic non-obese diabetic (NOD; NOD/ShiJcl) mice—a mouse model for Sjögren's syndrome—and found myoepithelial cells to be decreased or atrophied in the diabetic state.

Sonographic and CT findings of sialadenosis in a child with leukemia

Sialadenosis is characterized by asymptomatic bilateral enlargement of the parotid glands. It is uncommon, especially in children. Diagnosis and analysis of sialadenosis based on imaging modalities have been rarely reported. Here, we report a case of sialadenosis in a child with leukemia, in which the diagnosis was made based on sonography and CT findings.