Salivary mucins in host defense and disease prevention

Abstract

Mucus forms a protective coating on wet epithelial surfaces throughout the body that houses the microbiota and plays a key role in host defense. Mucins, the primary structural components of mucus that creates its viscoelastic properties, are critical components of the gel layer that protect against invading pathogens. Altered mucin production has been implicated in diseases such as ulcerative colitis, asthma, and cystic fibrosis, which highlights the importance of mucins in maintaining homeostasis. Different types of mucins exist throughout the body in various locations such as the gastrointestinal tract, lungs, and female genital tract, but this review will focus on mucins in the oral cavity. Salivary mucin structure, localization within the oral cavity, and defense mechanisms will be discussed. These concepts will then be applied to present what is known about the protective function of mucins in oral diseases such as HIV/AIDS, oral candidiasis, and dental caries.

Glycan recognition at the saliva – oral microbiome interface

“…Salivary mucins are the most densely glycosylated proteins in saliva and play an important role in oral host defense [51, 52] (Fig. 2).…”

Oral Helicobacter pylori: Interactions with host and microbial flora of the oral cavity

“…More than 20 mucins covering the epithelial surface of the respiratory, digestive and reproductive tracts have been detected in the human body. 4 MUC1, MUC4, MUC19, MUC5B and MUC7 are produced in the oral cavity, while the dominant and most important groups are the last two. 4,5 MUC5B is a compound with a molecular weight in excess of 1000 kDa and consists of disulfide-bonded subunits.…”

“…4 MUC7 is a secretory mucin present in the form of monomers (180-200 kDa) or dimers. It is located mainly in the submandibular and sublingual salivary glands.…”

“…It is located mainly in the submandibular and sublingual salivary glands. 3,4 Mucins and defense proteins play a crucial role in the formation of acquired pellicle, i.e., a thin layer (0.5-1 μm) of saliva components with the ability to bind to calcium hydroxide. These components have receptors for microbes and, thus, in the surface immune exclusion process, contribute to the immobilization of microorganisms and protection against host tissue invasion.…”

“…3,5 Despite the protective function, this process also has a disadvantageous aspect associated with the formation of biofilm by microorganisms colonizing the oral cavity. 3,4 Populations of microbes often form highly organized complexes called biofilms. These structures are made up of microbial cells embedded within the extracellular matrix, which accounts for nearly 90% of biofilm and consists of exopolysaccharides, proteins, lipids and extracellular DNA (eDNA).…”