Immunoglobulin A defines secretions from salivary tissue in post-Sistrunk procedure drainage.

OBJECTIVES: This was a pilot study to establish a protein difference between thyroglossal duct cyst fluid relative to oral saliva, in order to differentiate patients with residual thyroglossal cyst from those with salivary fistula in the case of post-Sistrunk procedure incisional drainage. Past immunohistochemistry studies on archived tissue blocks from post-Sistrunk procedure patients have shown MUC5AC to have elevated concentrations in thyroglossal duct relative to salivary tissue; secretory immunoglobulin A (IgA) was also chosen as a candidate protein based on previously published reports of its increased concentration in saliva relative to respiratory secretions. DESIGN: Diagnostic tests were assessed. Thyroglossal duct cyst fluid and oral saliva were obtained from 12 patients. Enzyme-linked immunosorbent assay (ELISA) was then performed on the samples to identify the presence of MUC5AC and IgA. SETTING: Tertiary care hospital. SUBJECTS: Patient fluid samples were taken immediately postoperatively for patients undergoing Sistrunk procedure at one institution. Presence of thyroglossal duct cyst was confirmed in all cases by pathology. RESULTS: Seven of 12 thyroglossal duct cyst fluid samples were shown to have elevated absorbance with ELISA for MUC5AC. In experiments for IgA, 10 of the 12 saliva samples had elevated absorbance compared with thyroglossal duct fluid samples obtained from the same patient. CONCLUSIONS: IgA is an accurate identifier of saliva compared with thyroglossal duct fluid in secreted samples obtained from the same patient.

Matrix metalloproteinase inhibition causes luminal narrowing and ring thickening in the cricoid cartilage.

OBJECTIVE: Luminal expansion of the cricoid cartilage appears to be stunted by loss of luminal epithelium (LE) and can be enhanced by transforming growth factor-beta3 (TGF-beta3). When both the LE and perichondrium are disrupted, matrix metalloproteinase (MMP) levels within adjacent chondrocytes are diminished but can be restored by exogenous TGF-beta3. Cricoid growth stunting and luminal expansion that occur in the absence and presence of MMP activity, respectively, suggest that MMPs play an important role in normal subglottal development. The study objective was to determine if MMP inhibition affects cricoid expansion and by what mechanism, which will in turn help to define the mechanism of action of TGF-beta3-induced luminal expansion. STUDY DESIGN: Ex vivo, in vitro whole organ culture of subglottises grown with and without the presence of an MMP inhibitor. SETTING: Tertiary care facility. SUBJECTS AND METHODS: Subglottises from 20 neonatal mice were divided into 10 grown with an MMP inhibitor, GM6001, and 10 grown in basic medium alone. The luminal cross-sectional area, apoptosis levels, cell proliferation rates, and presence or absence of cleaved aggrecan fragments were determined. RESULTS: Subglottises that were exposed to the MMP inhibitor displayed statistically significant luminal narrowing, accompanied by apparent circumferential thickening of the cricoid ring, relatively decreased apoptosis, increased chondrocyte proliferation, and decreased amounts of aggrecan cleavage fragments in the extracellular matrix. CONCLUSION: Matrix metalloproteinases likely play a significant role in growth of the cricoid cartilage such that their inhibition leads to marked changes in the shape of the ring.

Drainage post-thyroglossal duct remnant surgery: possible source and analysis.

OBJECTIVE: To establish the distance between tongue base salivary tissue and hyoid. Also, to identify protein differences between thyroglossal duct (TGD) remnants and salivary tissue in order to distinguish drainage source post Sistrunk surgery. METHODS/SETTING: The anterior neck block was obtained from 10 adult cadavers with no known neck pathology. The distance between the normal salivary tissue and hyoid was measured histologically. Immunohistochemistry (IHC) was then performed on 20 archived tissue blocks from pediatric patients post Sistrunk surgery to identify the presence of amylase, MUC5AC (tracheobronchial mucin), and MUC7 (salivary mucin) within the excised specimen. RESULTS: Average distance between salivary tissue and the hyoid within adult human cadavers was 3.3 mm (range, 1.0-4.2 mm). IHC revealed all excised TGD remnants contained amylase and MUC5AC but none contained MUC7. Both amylase and MUC7 were present within adjacent salivary tissues. CONCLUSIONS: Salivary tissue of the tongue base normally resides an average of 3.3 mm from the hyoid within the adult population. Biochemical analysis showed MUC5AC was specific for TGD remnants while MUC7 was specific for salivary tissue. Amylase does not distinguish between the two tissues.

Transforming growth factor beta3 increases chondrocyte proliferation and decreases apoptosis in murine cricoid cartilage in vitro.

OBJECTIVE: To determine if the luminal epithelium and/or exogenous transforming growth factor beta (TGFbeta) affects growth of the cricoid. DESIGN: Subglottises from 20 neonatal mice were subdivided into four groups: A, five subglottises with luminal epithelium grown in basic medium; B, five epithelium-free subglottises in basic medium; C, five epithelium-free subglottises in basic medium with supplemental TGFbeta1, and D, five epithelium-free subglottises in basic medium with supplemental TGFbeta3. RESULTS: Groups A and D demonstrated the greatest luminal area expansion. Group A rings demonstrated statistically higher chondrocyte proliferation than Groups B and C and lesser amounts of luminal apoptosis. Groups B and C rings demonstrated the least amount of cell proliferation, and greater luminal apoptosis relative to Group A. Groups A and D rings had similar apoptotic and proliferative results. CONCLUSIONS: Luminal epithelium exerts influence over the cricoid by increasing chondrocyte proliferation and decreasing the relative proportion of luminal chondrocytes that undergo apoptosis. Exogenous TGFbeta3, not TGFbeta1, also increases chondrocyte proliferation within the cricoid and appears to influence apoptosis as well.

Matrix metalloproteinases 2 and 9 are concentrated in the luminal aspect of the cricoid cartilage, diminish with loss of perichondrium, and are reinstated by transforming growth factor beta 3.

OBJECTIVES: We determined the location of matrix metalloproteinases (MMP) 2 and 9, and whether the luminal perichondrium or transforming growth factor (TGF) beta3 influences the presence of MMP-2 and/or -9 within the chondrocytes of the cricoid cartilage. METHODS: Subglottises from 15 neonatal mice were divided into group A (N = 5; luminal epithelium intact, grown in basic medium), group B (N = 5; epithelium-free, with sections of luminal perichondrium removed, grown in basic medium), and group C (N = 5; epithelium-free, with sections of luminal perichondrium removed, grown in basic medium with supplemental TGF-beta3). Immunohistochemical analysis was done to identify MMP-2 and -9 distributions. RESULTS: Group A demonstrated concentrations of MMP-2 and -9 in the luminal perichondrial and adjacent chondrocytes with a gradual decrease in signal intensity toward the outer perichondrium. Group B showed findings similar to those in group A, but in the region of removed perichondrium, the adjacent chondrocytes lost MMP-2 and -9 signal. The group C rings demonstrated reestablishment of MMP-2 and -9 signal in regions of luminal perichondrial loss. CONCLUSIONS: Localization of MMP-2 and -9 is predominantly in the luminal perichondrium and gradually decreases toward the outer perichondrium. The luminal perichondrium maintains expression of MMP-2 and -9 within the adjacent chondrocytes. Exogenous TGF-beta3 reestablishes production of at least MMP-9, and probably MMP-2, in cricoid cartilages missing luminal perichondrium.