Oral mucosal mucus layer

The oral mucosal mucus layer is a specialized viscoelastic gel that covers the surfaces of the oral cavity, serving as the first line of defense against environmental insults. It is primarily composed of water, electrolytes, and large, heavily glycosylated proteins called mucins, specifically MUC5B and MUC7, which are secreted by major and minor salivary glands [1]. This layer performs essential biological functions, including the lubrication of oral tissues to facilitate mastication and speech, the maintenance of mucosal hydration, and the provision of a semi-permeable barrier that traps pathogens and neutralizes toxins [2]. In pathological states such as xerostomia or radiation-induced oral mucositis, the depletion or degradation of this layer leads to painful ulcerations and increased susceptibility to infections [3]. Therapeutically, the oral mucus layer is targeted by salivary substitutes and mucosal protectants that aim to restore its barrier function and by mucoadhesive drug delivery systems designed to increase the local residence time of pharmacological agents [4]. These systems utilize polymers that interact with mucin chains through physical entanglement or chemical bonding to enhance drug bioavailability [5]. Citations: [1] Frenkel, E. S., & Ribbeck, K. (2015). Salivary mucins in host defense and oral health. Journal of Dental Research. [2] Tabak, L. A. (1995). In defense of the oral cavity: structure, biosynthesis, and function of salivary mucins. Annual Review of Physiology. [3] Sonis, S. T. (2004). The pathobiology of mucositis. Nature Reviews Cancer. [4] Shaikh, R., et al. (2011). Mucoadhesive drug delivery systems. Journal of Pharmacy & Bioallied Sciences. [5] Khutoryanskiy, V. V. (2011). Advances in mucoadhesion and mucoadhesive polymers. Macromolecular Bioscience.

Other names

Oral mucusSalivary mucus layerOral mucosal barrierSalivary pellicle

Mucoadhesion through non-covalent interactions and physical entanglement with mucin fibers; stimulation of endogenous secretion via muscarinic receptor agonism; and physical coating to provide a protective barrier.