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Objective Owing to variations in the exterior appearances of noncancerous diseases in the oral cavity, clinicians may have difficulty diagnosing oral squamous cell carcinoma (OSCC). Tissue biopsy is confirmatory, but invasive. Therefore, reliable tumor markers for OSCC are required. Here, exosomal Alix (exoAlix) levels were measured in serum/salivary samples from patients with OSCC and healthy controls (HCs). Methods Fifty-seven patients admitted to Nagoya University Hospital from 2017 through 2019 were enrolled, and serum samples (OSCC, n = 29; HC, n = 21) and/or saliva samples (OSCC, n = 23; HC, n = 20) were collected. Exosomal fractions were isolated using ultracentrifugation. ExoAlix levels were measured using enzyme-linked immunosorbent assay. Results Serum/salivary exoAlix levels were significantly higher in patients with OSCC than in HCs. Receiver operating characteristic analyses revealed that sensitivity, specificity, positive predictive value, and area under the curve were 0.345, 1.000, 1.000, and 0.685, respectively, for serum exoAlix and 0.348, 1.000, 1.000, and 0.712, respectively, for salivary exoAlix at optimal cut-off values (serum, 0.205; saliva, 0.193). All tested OSCC tissue sections (n = 21) were immuno-reactive for Alix. Conclusion Serum and salivary exoAlix were identified as potential diagnostic OSCC biomarkers. Serum exoAlix was suitable for prediction of therapeutic responses.

Subcutaneous emphysema of the face region has been reported to be a complication of dental procedures and trauma. Emphysema is usually self-limiting and is treated conservatively. This report describes a rare case of emphysema around the mandibular condyle, which did not recover naturally for more than 3 months. A 54-year-old man was referred for swelling of the left side of the face. While undergoing manual therapy at an osteopathic clinic, he heard an unusual noise and experienced severe pain in his left temporomandibular joint. Computed tomography of his head revealed massive air around the left condyle and fractures of the left condyle and glenoid fossa. These injuries were thought to have occurred during manual therapy at the osteopathic clinic. He was diagnosed with emphysema around the left side of the condyle and fractures of the left condyle and glenoid fossa. The injury generated an inflow path of air, with the emphysema thought to be caused by the surrounding soft tissue acting as a check valve. Condylar movement produced negative pressure within the joint space, trapping air in the extracapsular soft tissues. Movement of the masticatory muscle while eating may have acted as a pump to increase emphysema. The patient was treated with continuous negative pressure drainage, resulting in disappearance of the emphysema. This technique may be effective in treating subcutaneous emphysema of the face.

Exosomes are 50-100-nm-diameter membrane vesicles released from various types of cells. Exosomes retain proteins, mRNAs and miRNAs, which can be transported to surrounding cells. CD109 is a glycosylphosphatidylinositol-anchored glycoprotein, and is released from the cell surface to the culture medium in vitro. Recently, it was reported that secreted CD109 from the cell surface downregulates transforming growth factor-β signaling in human keratinocytes. In this study, we revealed that CD109 is a component of the exosome in conditioned medium. FLAG-tagged human CD109 (FLAG-CD109) in conditioned medium secreted from HEK293 cells expressing FLAG-CD109 (293/FLAG-CD109) was immunoprecipitated with anti-FLAG affinity gel, and the co-precipitated proteins were analyzed by mass spectrometry and western blotting. Exosomal proteins were associated with CD109. We revealed the presence of CD109 in exosome fractions from conditioned medium of 293/FLAG-CD109. Moreover, the localization of CD109 in the exosome was demonstrated using immuno-electron microscopy. When we used HEK293 cells expressing FLAG-tagged truncated CD109, which does not contain the C-terminal region, the association of truncated CD109 with exosomes was not detected in conditioned medium. These findings indicate that CD109 is an exosomal protein and that the C-terminal region of CD109 is required for its presence in the exosome.