Abstract
IntroductionNeurofibromin, a protein encoded by the NF1 gene, is mutated in neurofibromatosis 1, one of the most common genetic diseases. Oral manifestations are common and a high prevalence of hyposalivation was recently described in individuals with neurofibromatosis 1. Although neurofibromin is ubiquitously expressed, its expression levels vary depending on the tissue type and developmental stage of the organism. The role of neurofibromin in the development, morphology, and physiology of salivary glands is unknown and a detailed expression of neurofibromin in human normal salivary glands has never been investigated.AimTo investigate the expression levels and distribution of neurofibromin in acinar and ductal cells of major and minor salivary glands of adult individuals without NF1.Material and methodTen samples of morphologically normal major and minor salivary glands (three samples of each gland: parotid, submandibular and minor salivary; and one sample of sublingual gland) from individuals without neurofibromatosis 1 were selected to assess neurofibromin expression through immunohistochemistry. Immunoquantification was performed by a digital method.ResultsNeurofibromin was expressed in the cytoplasm of both serous and mucous acinar cells, as well as in ducts from all the samples of salivary glands. Staining intensity varied from mild to strong depending on the type of salivary gland and region (acini or ducts). Ducts had higher neurofibromin expression than acinar cells (p = 0.003). There was no statistical association between the expression of neurofibromin and the type of the salivary gland, considering acini (p = 0.09) or ducts (p = 0.50) of the four salivary glands (parotid, submandibular, minor salivary, and sublingual gland). Similar results were obtained comparing the acini (p = 0.35) and ducts (p = 0.50) of minor and major salivary glands. Besides, there was no correlation between the expression of neurofibromin and age (p = 0.08), and sex (p = 0.79) of the individuals, considering simultaneously the neurofibromin levels of acini and duct (n = 34).ConclusionNeurofibromin is expressed in the cytoplasm of serous and mucous acinar cells, and ductal cells of salivary glands, suggesting that this protein is important for salivary gland function.
Highlights
Neurofibromin, a protein encoded by the Neurofibromatosis 1 (NF1) gene, is mutated in neurofibromatosis 1, one of the most common genetic diseases
Neurofibromin was expressed in the cytoplasm of both serous and mucous acinar cells, as well as in ducts from all the samples of salivary glands
Neurofibromin is expressed in the cytoplasm of serous and mucous acinar cells, and ductal cells of salivary glands, suggesting that this protein is important for salivary gland function
Summary
Neurofibromin, a protein encoded by the NF1 gene, is mutated in neurofibromatosis 1, one of the most common genetic diseases. Neurofibromatosis 1 (NF1, OMIM 162,200) is one of the most frequent genetic diseases in humans and has an neurofibromin is ubiquitously expressed, its expression levels vary according to the tissue type and developmental stage [4]. None of the external factors related to hyposalivation (medication, smoking, low fluid intake, caffeinated and alcoholic beverages) was associated with a low salivary flow rate in individuals with NF1. These previous results suggest that alterations in neurofibromin due to mutations in NF1 gene, that occur in individuals with NF1, may be related to a reduction of salivary glands function. The role of neurofibromin in the development, morphology, and physiology of salivary glands is unknown and a detailed expression of neurofibromin in human salivary glands has never been investigated
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