Conclusions: We demonstrated that PLUNC (palate, lung, and nasal epithelium clone) is secreted from nasal epithelial cells and is not influenced by differentiation or proinflammatory mediators. The functional role of PLUNC in the human airway has yet to be elucidated.
Objectives: The localization and regulation of PLUNC protein in human nasal epithelium was investigated. First, we located epithelial cells expressing PLUNC protein in human nasal mucosa. Secondly, we sought to identify PLUNC protein in either human nasal secretions from healthy volunteers or apical secretions from cultured human nasal epithelial cells. Lastly, we investigated whether epithelial differentiation and proinflammatory cytokines influence the expression of PLUNC in human nasal epithelial cells.
Materials and methods: Immunohistochemical staining for PLUNC was conducted on nasal turbinate specimens. Western blot analysis was conducted on nasal secretions from healthy volunteers, apical secretion from cultured human nasal epithelium, and on normal-appearing posterior ethmoid mucosa, inferior turbinate, and nasal polyp specimens. Reverse transcription-PCR (RT-PCR) of PLUNC was performed with mRNA from cultured human nasal epithelium cells treated with either interleukin-1beta or tumor necrosis factor-alpha.
Results: PLUNC was expressed in ciliated cells of surface epithelium and serous cells of the submucosal gland in the human nasal mucosa, and was also found in the nasal secretions of healthy volunteers and apical secretions of cultured human nasal epithelial cells. The degree of mucociliary differentiation and proinflammatory mediators did not influence the expression of PLUNC gene and protein in nasal epithelium.