User:Coelacanth22/Salivary microbiome

Salivary microbiome

The salivary microbiome consists of the nonpathogenic, commensal bacteria present in the healthy human salivary glands.It differs from the oral microbiome which is located in the oral cavity. Unlike the salivary microbiome, which is typically concentrated in the salivary glands of a person, oral microorganisms tend to adhere to teeth. The salivary microbiome is unique and is made up of microbiota which can greatly differ from those found in other microbiomes. It is possible that there are significant connections between microbiota of the mouth and human body, especially those belonging to the intestinal tract. Studies done on the salivary microbiome could lead to robust methods of diagnosing disease, allowing for better understandings of how the salivary microbiome is an indicator of health.

Microorganisms reside in saliva

Characteristics

Unlike the uterine, placental and vaginal microbiomes, the types of organisms in the salivary microbiota remain relatively constant. Numerous studies have demonstrated that although there can be small changes in these microbiomes due to temporal shifting, such as the changing of seasons, most microbiomes remain relatively stable . There is no difference between populations of microbes of based upon gender, age, alcohol intake, race, or tobacco use. The salivary microbiome characteristically remains stable over a lifetime, which may indicate that environmental factors that the host resides in are more responsible for the specific microbiota found in the salivary glands. However, research has shown that it is possible that diet and lifestyle can have an impact on the different types of bacterial microbiota found in the mouth. There are also studies which suggest that obesity can also affect the salivary microbiome, as controls in such experiments displayed higher levels of microbiota diversity when compared to people with obesity. One study suggests sharing an environment (e.g., living together) may influence the salivary microbiome more than genetic components. Porphyromonas, Solobacterium, Haemophilus, Corynebacterium, Cellulosimicrobium, Streptococcus and Campylobacter are some of the genera found in the saliva.

Genetic markers and diagnostic testing

Salivary microbiome testing is an avenue of diagnostic testing which has not been full developed, but may have potential as a new path in health indication since saliva is typically a preferred method of gathering a person's DNA. Although there is high diversity between the salivary microbiomes of different individuals, this diversity seems to be more related to the natural variance of genetic markers found in human populations. The diversity amongst the different microbiomes of individuals in separate geographic locations is comparable to the natural differences as a result of genetic variance.

Microscopic image of the microbiome of a human mouth

One possible significant geographic factor is the distance between locations to the equator, which has shown to exhibit increased genetic diversity. However, other variables could be at play here, including UV index, which could have an affect on the types of salivary microbiota found in populations of different locations.

Sixty new genera have been identified from the salivary glands. A total of 101 different genera were identified in the salivary glands. Out of these, 39 genera are not found in the oral microbiome. It is not known whether the resident species remain constant or change.

Though the association between the salivary microbiome is similar to that of the oral microbiome, there also exists an association the salivary microbiome and the gut microbiome. Saliva sampling may be a non-invasive way to detect changes in the gut microbiome and changes in systemic disease. The association between the salivary microbiome those with Polycistic Ovarian Syndrome has been characterized: "saliva microbiome profiles correlate with those in the stool, despite the fact that the bacterial communities in the two locations differ greatly. Therefore, saliva may be a useful alternative to stool as an indicator of bacterial dysbiosis in systemic disease." Salivary microbiome testing done on patients has also shown the possibility of diagnosing other diseases, including diabetes, cancer, rheumatoid arthritis, and HIV, based on how these diseases influence levels of specific bacteria in the mouth.

Salivary glands: 1.parotid, 2.submandibular, 3.sublingual.

The sugar concentration in salivary secretions can vary from person to person, and they may reveal different states of health depending on the differences. Blood sugar levels are reflected in salivary gland secretions because saliva is the ultrafiltrate of blood, meaning that it is the liquid that blood cells travel in throughout the body. High salivary glucose (HSG) levels are a glucose concentration ≥ 1.0 mg/d, n = 175) and those with low salivary glucose (LSG) levels are < 0.1 mg/dL n = 2,537). Salivary gland secretions containing high levels of sugar change the oral microbiome and contributes to an environment that is conductive to the formation of dental caries and gingivitis.

Salivary glands

Organisms of the salivary microbiome reside in the three major salivary glands: parotid, submandibular, and sublingual. These glands secrete electrolytes, proteins, genetic material, polysaccharides, and other molecules. Most of these substances enter the salivary gland acinus and duct system from surrounding capillaries via the intervening tissue fluid, although some substances are produced within the glands themselves. The level of each salivary component varies considerably depending on the health status of the individual and the presence of pathogenic and commensal organisms.