Unique Oral Bacteria in Lupus

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The microbiome – the bacteria, viruses, fungi and other microorganisms that naturally live in the mouth – of people with lupus are unique, even when under treatment.

People with lupus have a unique variety of species of bacteria and microorganisms in their mouth. In fact, not only do they have a greater variety of species of oral bacteria living in their mouths, but also different levels of certain types of bacteria.

Why is this important? First, it is important to understand that we do not live our lives totally on our own – each one of us carries millions of bacteria, viruses, fungi and other microorganisms on and in our bodies… and this is completely healthy! These microorganisms form complicated communities called microbiomes, and different parts of our bodies can have wildly different species that call them home. Best known from popular culture is the gut microbiome, the microbes that call our intestines home, help us digest food, produce essential nutrients, help with metabolism control and fat storage, and protect us from disease. For people with lupus, a healthy microbiome, maybe supported with a good, balanced probiotic diet, might reduce inflammation and make the symptoms of lupus better. 

However, other parts of our bodies have their own important communities, including the genitals, different areas of the skin, the lungs, and the mouth. In order to support good health, these communities also need to be healthy, with certain species of microbe more common than others.

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What is the Oral Microbiome?

The mouth microbiome is a term for the many species of bacteria that live in the mouth. In general, we inherit a lot of our microbiome communities from our mothers, but not all of it. Most of our resident microbes come from the environment – what we eat, touch, or breathe in. People even transmit their microbiomes to each other. Pollution in the air, water, or soil is also a huge factor, although surprisingly not pets. Pets actually have their own microbiomes, and the bacteria, viruses, and other microbes that live with them do not do so well in human bodies.

Bacteria in the mouth are important to the health of the teeth, gums, and even the whole body. As one of the areas of the body that is not only the most in contact with the outside world and also the most hospitable to growing microbes. The mouth is a very wet and nutrient-rich place to live, sort of like the body’s version of a rainforest. Because of this, the mouth is under constant pressure from invading microbes. It has a few defenses against harmful bacteria, including acidic and enzyme-rich saliva, mucous that captures microbes and potentially harmful substances, and, of course, the microbiome itself.


When healthy, the bacteria in your mouth can prevent other species from attaching themselves to the teeth and gums, kill infectious microbes by secreting antimicrobial substances, and reduce inflammation. They also help regulate the pH of the saliva, keeping it acidic enough to kill invaders, but not so acidic that it dissolves the teeth and contributes to tooth decay. If the saliva is too acidic, it stops important enzymes like the carbohydrate-digesting enzyme amylase from working in the mouth, too. 

Some bacteria in the mouth actually prevent the formation of plaques – a plaque is a sheet of bacteria that is attached to a surface, such as the outside of a tooth, and to each other. When they band together like this, they protect each other from being scraped off, killed by acid or enzymes, and from the actions of the immune system, making them difficult to get rid of. This type of bacterial teamwork is also called a biofilm, and in the mouth, they are notorious for irritating the gums and promoting tooth decay and gum disease. Some members of the microbiome prevent these biofilms from forming by binding to the problem bacteria instead, keeping them away from the gums. 

So how does the microbiome affect diseases like lupus?


What Throws off the Oral Microbiome?

The microbiome, wherever it’s found, generally helps with controlling the immune system, reducing inflammation, preventing “bad” microbes from causing trouble, and producing nutrients either for the human host or for other microbes that live near it. When the microbiome is not healthy, it fails to do these things and the species that live in that microbiome change. Non-communicable diseases such as lupus and cancer might have a link to microbiomes that are “off” in some way. To a degree, this can be inherited – Because your mother gives you a lot of your starting microbiome at birth and while you are an infant, if your mother has oral health problems or poor mouth hygiene habits (or smokes,) you will get her unhealthy microbiome. This will make you more likely to have oral health problems, too, in the future even if your behavior is completely different because of the microbes that she gave you. Your environment and behavior also change what species find your body hospitable, and one of those factors is any diseases that affect your body. 

So do unusual microbiomes cause disease, or are they a symptom of disease? The answer may be both. Typically, researchers find, the bacteria aren’t causing the sickness, usually, but something about what they are producing, or the amounts they are producing certain substances in, might make one susceptible to other disorders. By being more susceptible to diseases, this may make the microbiome’s environment more welcoming to species that will make a person’s health conditions worse, creating a feedback loop. 

This makes the microbiome both important to maintaining health and, for some, a great early indication that something isn’t right. 

Important Study on the Oral Microbiome and Lupus

A person with lupus is at higher risk of oral health issues, and this might be, in part, because of the microbiome of the lupus in their mouth.

In the Chinese study on the oral microbiomes of people with lupus, 462 people (182 people with SLE and 280 people who were matched as Healthy controls without other oral issues such as periodontal disease) had their bacteria compared to each other. They had their oral bacteria sequenced by taking a sample from their tongues and looking at the bacteria in their mouths. 73 of the people with SLE were also sequenced after treatment for SLE to see if the treatment changed their microbiome significantly. 

Disease activity in SLE seems to be reflected in the microbiome of the mouth. When the people with SLE in the study were split into mild, moderate, and severe symptom groups, they did seem to have unique microbiome profiles. After treatment, people with stable SLE, or SLE that was pushed into remission, had a unique microbiome profile that was both distinct from others with SLE and also from healthy controls. This supports the idea that SLE cannot be cured, only treated, and also that even in people with low or covert symptoms, the microbiome remains stable and consistent across the many different ways that SLE can show itself. It also implies that major SLE symptoms might not be directly related to the oral bacteria. Is it something about the mouths of people with SLE that is different, perhaps their saliva production – this is unknown, but the stability found in this admittedly small study is remarkable! The oral bacteria did not return to “normal.” Notably, studies in rheumatoid arthritis seemed to imply that treatment did bring the oral microbiome close to normal levels of diversity.


The Oral Microbiome and Lupus – What’s the Point?

The oral microbiome might be involved in both the development of SLE and recovery from SLE.

Aside from the broad strokes of the normal microbes living in the mouth protecting the teeth, gums, mouth tissues, and body from disease and damage, we still know very little about the microbiome. Like other parts of the microbiome, the exact proportions of bacteria, viruses, and other microorganisms are highly dependent on one’s environment, including the air around us and the food that we eat. One of the reasons that sugar can cause cavities, for example, is that it feeds certain types of bacteria that then produce acidic substances. These bacteria also then reproduce to higher levels and form plaques on the teeth, which makes them harder to get rid of.

Acids in the mouth can dissolve the enamel beyond the ability of the mouth to repair it, revealing the softer layer known as dentine. While enamel is one of the hardest materials that the human body can produce, dentine is fairly soft and can be easily damaged. This is how cavities are formed. You can read more about tooth decay and lupus here

Many people with lupus experience feelings of stickiness and dryness in their mouth because their mouths do not produce enough saliva. Saliva, notably, lowers the PH of the mouth and has enzymes that prevent infection. SLE can attack the salivary glands, making them unable to produce enough saliva. This can actually make SLE worse, since a drier mouth can be a great place for infections to take hold, leading to inflammation, which then triggers more symptoms of lupus. Aside from triggering flares and causing infections, dry mouth can lead to tooth decay and wounds in the skin of the mouth called lesions or ulcers.

We also know that antibodies to oral bacteria are linked to more severe SLE symptoms. The bacteria are more likely to end up in the bloodstream or another part of the body where it comes into contact with the immune system. Whether this is the cause of or an effect of low-grade inflammation found in lupus is unclear. It could also be both. https://www.webmd.com/oral-health/probiotics-gum-disease Bacteria buildup near the gums cause inflammation, which can exacerbate lupus symptoms and cause worse buildups of bacteria. This is also known as gingivitis or gum disease.  Oral bacteria can also affect wound healing and the formation of ulcers in the mouth, a common symptom of lupus. You can read more about mouth sores and lupus here


Taking Care of Your Oral Microbiome

While we don’t entirely understand how the microbiome works, changing the microbes in the mouth and gut is a possible way to improve health for people with lupus. Because you are, to a degree, what you eat, taking care of the mouth takes care of nearly the whole body: Improving your oral health can improve your heart health, safeguard against many pregnancy complications, and protect against pneumonia. Bacteria from the mouth can end up in the stomach, lungs, and bloodstream, so if the microbiome is disrupted infections can occur there too.

Fortunately, it’s very easy to manage the oral microbiome – anything that you put into your mouth effects the microbiome there, and you have almost complete control over that. One the easiest method is by changing diet. By changing what bacteria and nutrients enter the mouth and gut, one can change what lives in these areas. 

Sugar-rich diets and poor dental hygiene allow non-beneficial bacteria to proliferate. These bacteria produce acid, which lowers the PH of the mouth and dissolves the teeth, making it easier for cavities and dental caries to form. Tooth decay is no joke. The answer, then, is lower sugar diets and regular tooth brushing, flossing, and dental checkups. Caffeine intake should be done in moderation. Many caffeine containing beverages are acidic and caffeine has a dehydrating effect. But some, such as plant-derived tea and coffee, also have antioxidants and other anti-inflammatory nutrients that can have health benefits for people with lupus.

Probiotics can help with both gut and mouth health. Probiotics are microorganisms that potentially offer health benefits when eaten or taken with a supplement. Although most microorganisms die off when eaten due to various defenses in the body, some of these “good bacteria” can find a home in the mouth and gut. Having healthy levels of these “good” bacteria are associated with health benefits, including anti-inflammatory benefits for people with lupus. Good bacteria can be encouraged by eating a balanced diet rich in sources of this bacteria and the nutrition that they need to thrive.

A great way to get probiotics in both places is to eat fermented foods such as yogurt, pickles, or kimchi, as the bacteria can colonize both the mouth. These foods are also often vitamin-rich, though many pickles use an acidic brine which can potentially make tooth decay worse or use a sugar brine that feeds destructive bacteria. Frequent brushing should make this less of an issue, however. 

Fiber-rich foods like Leafy greens, bananas, asparagus and apples also encourage the growth of the bacteria that you want and should be part of a balanced anti-inflammatory diet anyway.  You can read more about the benefits of fiber for people with lupus here.  Although people with lupus should not eat garlic due to its immune system-stimulating substances that increase inflammation in the body, and thus damage from lupus, it is also considered a good probiotic food.  

Oral hygiene is also a key factor. Toothbrushing regularly (twice a day is recommended,) flossing, and using mouthwashes can help keep oral health – including the oral microbiome- in top shape. However, be careful of harsh mouthwashes containing alcohol. Although mouthwashes help oral ulcers heal, they can also dry o ut the mouth and irritate the inside of the mouth, which can make symptoms worse. Saltwater rinses are gentle and do not cause drying, but fluoride-containing mouthwashes are also recommended by the American Dental Association.


A Few Good Oral Hygiene Practices

Hygiene is already vital for people with lupus, oral hygiene no less so. 

Here are a few tips on how to maintain good, tooth-sparkling oral health:

  • Brush teeth with a soft-bristled brush, fluoride toothpaste, twice a day for two minutes each. The toothbrush should be replaced and refreshed every couple of months.
  • Floss daily to prevent colonies from forming in between the teeth.
  • A healthy diet for lupus is low in sugars and processed foods. Sugarv is found in a lot of foods you wouldn’t expect, too, so check those labels!
  • Use a mouthwash to remove food particles and clear out unwanted bacterial colonies that remain after brushing and flossing. However, be careful with mouthwash, as certain kinds can also dry out the mouth and cause issues of their own.
  • Avoid alcohol and tobacco use – Smoking changes the PH of the mouth, introduces and feeds microorganisms that you do not want to be there, and also dehydrates the mouth and airways. Drinking alcohol is overall not recommended for people with lupus, for many of the same reasons. 
  • Visit the dentist regularly and get regular checkups and cleanings.

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