Organoid Models for Salivary Gland Biology and Regenerative Medicine

The salivary gland is composed of an elegant epithelial network that secrets saliva and maintains oral homeostasis. While cell lines and animal models furthered our understanding of salivary gland biology, they cannot replicate key aspects of the human salivary gland tissue, particularly the complex architecture and microenvironmental features that dictate salivary gland function. Organoid cultures provide an alternative system to recapitulate salivary gland tissue in vitro, and salivary gland organoids have been generated from pluripotent stem cells and adult stem/progenitor cells. In this review, we describe salivary gland organoids, the advances and limitations, and the promising potential for regenerative medicine.

A case report of ectopic salivary gland tissue in the larynx

Submucosal laryngeal masses are challenging for ENT specialists as the diagnosis usually remains uncertain until histopathological examination is carried out. We report a case of a 54-year old man complaining of dysphonia and globus sensation. Flexible laryngoscopic examination showed a submucosal swelling in the right anterior laryngeal ventricle. Microlaryngoscopic excision of the submucosal mass was performed. Histological examination revealed salivary gland tissue. We found only a few cases in the literature of ectopic salivary gland tissue situated in the larynx. In these cases, the salivary gland tissue was also located at the anterior portion of the true or false vocal fold. Thus, it is necessary to consider this condition in the differential diagnosis of a submucosal mass in the anterior true or false vocal fold or laryngeal ventricle.

The Transcriptome of Paired Major and Minor Salivary Gland Tissue in Patients With Primary Sjögren’s Syndrome

BackgroundWhile all salivary glands (SGs) can be involved in primary Sjögren’s syndrome (pSS), their respective role in pathogenesis remains unclear. Our objective was to assess immunopathway activation in paired parotid and labial gland tissue from biopsy-positive and biopsy-negative pSS and non-SS sicca patients.MethodsParaffin-embedded, paired parotid and labial salivary gland tissue and peripheral blood mononuclear cells were obtained from 39 pSS and 20 non-SS sicca patients. RNA was extracted, complementary DNA libraries were prepared and sequenced. For analysis of differentially expressed genes (DEGs), patients were subdivided based on fulfillment of ACR-EULAR criteria and histopathology.ResultsWith principal component analysis, only biopsy-positive pSS could be separated from non-SS sicca patients based on SG gene expression. When comparing the transcriptome of biopsy-positive pSS and biopsy-negative non-SS sicca patients, 1235 and 624 DEGs (FDR<0.05, log2FC<-1 or >1) were identified for parotid and labial glands, respectively. The number of DEGs between biopsy-negative pSS and non-SS sicca patients was scarce. Overall, transcript expression levels correlated strongly between parotid and labial glands (R2 = 0.86, p-value<0.0001). Gene signatures present in both glands of biopsy-positive pSS patients included IFN-α signaling, IL-12/IL-18 signaling, CD3/CD28 T-cell activation, CD40 signaling in B-cells, DN2 B-cells, and FcRL4+ B-cells. Signature scores varied considerably amongst pSS patients.ConclusionTranscriptomes of paired major and minor SGs in pSS were overall comparable, although significant inter-individual heterogeneity in immunopathway activation existed. The SG transcriptome of biopsy-negative pSS was indistinguishable from non-SS sicca patients. Different patterns of SG immunopathway activation in pSS argue for personalized treatment approaches.

Further Research Needed to Understand Relationship Between Tubarial Glands and Eustachian Tube Dysfunction

The pathophysiology of eustachian tube dysfunction (ETD) remains poorly characterized, and it may result in significant patient morbidity. A recent study has identified a collection of previously unidentified salivary glands in the nasopharynx that overlay the torus tubarius. While salivary gland tissue has been described in the nasopharynx, the newly discovered salivary gland tissue has been denoted tubarial glands (TGs) and theorized to be a distinct organ. The TGs have been suggested to aid in lubrication of the oropharynx and nasopharynx. However, the exact clinical significance of TGs is unknown. Given the proximity of the TG to the eustachian tube, it is possible that the TGs may be related to the development of ETD. Future studies of the TGs and related pathophysiology may improve approaches to developing future ETD treatments.