The Oral Microbiome & Chronic Kidney Disease

The oral microbiome plays an essential role in the incidence and development of oral diseases, but did you know there is a connection between the oral microbiome and chronic kidney disease (CKD)? Did you know the oral microbiome is crucial in general oral and systemic health?

Amazingly, the oral cavity has the second largest and most diverse microbiota after the gut, with over 700 species of bacteria!

The oral microbiome refers to the diverse community of microorganisms that inhabit the mouth. This includes viruses, bacteria, fungi, and archaea. Imbalances in the oral microbiome have been implicated in various systemic diseases, including kidney disease, high blood pressure, and cardiovascular disease.

The teeth, tongue, cheeks, soft and hard palate, and gingival sulcus provide a rich environment for bacteria to thrive. These microorganisms play a crucial role in maintaining oral health; however, their influence extends far beyond teeth and gums.

Oral microbiome: Unveiling the fundamentals – PMC (nih.gov)

The Dutchman Antony van Leeuwenhoek identified the oral microbiome. In 1674, he reported seeing “little living animalcules prettily moving, using a microscope he constructed.

The human microbiome consists of a core microbiome and a variable microbiome. While the core microbiome is common to all individuals, the variable microbiome is unique to each individual, depending on lifestyle and physiological differences.

Oral microbiome: Unveiling the fundamentals – PMC (nih.gov)

What Causes Oral Dysbiosis?

Oral dysbiosis occurs when the balance of the oral microbiome is disrupted, allowing pathogens to thrive and cause disease.

• Inadequate care of your teeth, flossing and brushing can lead to an overgrowth of harmful bacteria.
• Consuming a high carbohydrate, high sugar diet provides a wonderful environment for pathogenic bacteria to make a cosy home.
• Smoking and consuming alcohol alter the oral microbiome and encourage dysbiosis.
• Chronic stress impacts the immune system and can influence the balance of oral microorganisms.
• Medications such as antibiotics cause significant alterations within the body’s microbiome. They can reduce beneficial bacteria and suppress the immune system. The oral contraceptive pill has also been shown to disrupt both the vaginal and gastrointestinal microbiome.
• Oral dysbiosis can be seen in conditions such as diabetes, arthritis, Parkinson’s disease, immunosuppression and COPD.

Imbalances in the Oral Microbiome & Kidney Disease

The oral cavity and nasopharyngeal region provide a perfect environment for these essential microorganisms. On average, the normal temperature of the oral cavity is 37 degrees Celsius without too much deviation. Saliva has a stable pH of 6.5-7, a beneficial pH for most species of bacteria. The perfect temperature provides bacteria with a stable environment to survive. Saliva keeps bacteria well hydrated and serves as a medium for the transportation of nutrients to microorganisms. However, sometimes things go astray.

Source Microorganisms | Free Full-Text | The Human Oral Microbiome in Health and Disease: From Sequences to Ecosystems (mdpi.com)

Several mechanisms have been proposed to explain the connection between the oral microbiome and kidney disease;

Inflammation

Chronic inflammation triggered by oral infections, such as gum disease, can contribute to systemic inflammation, which we know is a risk factor for kidney disease. Inflammatory mediators can enter the bloodstream and potentially impact kidney function.

There is a strong correlation between periodontitis and kidney disease. Periodontitis is a chronic inflammatory condition impacting the gums and teeth. Periodontitis and CKD share many of the same risk factors, such as obesity, smoking and age.

Research supports the role of periodontal inflammation and increased inflammatory mediators in renal atherosclerosis, renal deterioration and end-stage renal disease (ESRD) development. Clinical evidence suggests periodontal treatment will improve renal function. It has also been shown that poor oral health is a predictor of mortality in patients going through haemodialysis. Studies show that periodontitis is implicated in the development of persistent disease and is highly prevalent in chronic inflammatory disease.

Cytokines such as IL-1, IL-6, IL-8, IL-17, and TNF-α are associated with periodontitis and kidney disease. Periodontal tissues will produce inflammatory cytokines, which are translocated to the kidneys via blood circulation. Based on studies, it has been hypothesized that the pathogenic bacteria set by periodontitis may cause the release of cytokines by immune cells in the blood, causing kidney damage. In ischaemic mice, it has been shown that IL-6 further increases renal inflammation by recruiting more neutrophils to the damaged kidneys, aggravating acute renal failure.

Periodontitis Exacerbates and Promotes the Progression of Chronic Kidney Disease Through Oral Flora, Cytokines, and Oxidative Stress – PMC (nih.gov)

Image via Periodontitis Exacerbates and Promotes the Progression of Chronic Kidney Disease Through Oral Flora, Cytokines, and Oxidative Stress – PMC (nih.gov)

Periodontal Disease and Chronic Kidney Disease: The Impact of Oral Health on Inflammation and Nutrition in Patients Undergoing Hemodialysis | Current Oral Health Reports (springer.com)

Immune Response

Dysbiotic changes in the oral microbiome can lead to immune system activation. In some people, this immune response may become dysregulated and contribute to the development and progression of KD. The oral cavity is a portal of entry for both pathogens and antigens; the immune system in saliva plays a vital role in defence against any possible microbial invasion. An imbalance or dysbiotic changes in the salivary microbiome can trigger immune dysregulation, leading to chronic inflammation and immune system activation. Once again, chronic inflammation is a known risk factor for KD and has been implicated in the pathogenesis of CKD and glomerular nephritis. The kidneys are very susceptible to immune-mediated disease, the loss of immune homeostasis can directly or indirectly impact kidneys, ultimately leading to a loss of function.

Renal disease associated with the loss of immune homeostasis can be classified as direct or indirect immune-mediated kidney damage. Direct immune-mediated renal disease is seen when the immune system targets specific antigens within the kidney. Indirect immune-mediated kidney disease is where the kidneys are a bystander victim of processes resulting from systemic immune system dysregulation.

Overall disruption of immune homeostasis can lead to direct kidney disease through the overactivity of B and T cells, these cells can damage the kidneys at different sites.

The role of the immune system in kidney disease – PMC (nih.gov)

Image via The role of the immune system in kidney disease – PMC (nih.gov)

Bacterial Translocation

Pathogenic bacteria from the mouth can enter the bloodstream through the gums, especially in those with compromised oral health. Bacteria can travel to the kidneys and contribute to renal tissue infection or inflammation.

Research shows the saliva in patients with CKD exhibits distinct changes;

• Increased levels of Lautropia and Pseudomonas.
• Decreased levels of Actinomyces, Prevotella, Prevotella 7, and Trichococcus

Of interest, there is no significant difference in bacterial community in those with CKD, those with or without diabetes and patients with or without hypertension. The authors concluded that the co-occurrence of diabetes and hypertension is not associated with specific bacterial changes, suggesting oral dysbiosis plays a role in renal damage regardless of the occurrence of diabetes or hypertension.

Salivary microbiome in chronic kidney disease: what is its connection to diabetes, hypertension, and immunity? | Journal of Translational Medicine | Full Text (biomedcentral.com)

Oral pH, Blood Pressure & Kidney Disease

Are you a mouth breather?

If so, you are more likely to have an acidic mouth pH. An excellent oral pH is essential, and here is why.

If pH is not correct, it sets you up for:

• The wrong oral flora is growing.
• Your bacterial balance will be off.
• You don’t make the enzyme nitric oxide synthase made by bacteria at the bottom of your tongue.

A balanced microbiome also plays a crucial role in maintaining cardiovascular health. Nitric oxide synthase is responsible for the production of nitric oxide from the amino acid L-arginine. When the pH of the mouth becomes too acidic (typically below 5.5), it can lead to demineralization of tooth enamel, making teeth more susceptible to decay and erosion.

Another important process involves the conversion of dietary nitrate to nitric oxide, which helps regulate blood pressure and cardiovascular function. If your oral pH is unbalanced, the bacteria essential for healthy blood pressure may not be present and able to do their job.

Nitric oxide has been shown to have beneficial effects on heart health.

These include:

• Reduced blood pressure
• Reduced arterial stiffness
• Improvement in blood flow in the carotid artery

Unfortunately, most studies are on animal models, so we require more human studies to support these findings. NO has been shown to protect against the initiation and progression of atherosclerosis in many ways. NO produced from l-arginine regulates endothelium-dependent vasodilation and prevents the adhesion of blood cells and platelets along the endothelial layer of blood vessels.

Oral supplementation with a combination of l-citrulline and l-arginine rapidly increases plasma l-arginine concentration and enhances NO bioavailability – ScienceDirect

You can read all about nitric oxide in an article I have previously written, Nitric Oxide & Kidney Health – Kidney Coach;

Maintaining Good Oral Hygiene

I hope this incentivises you to look after your teeth and support good oral health.

 Following are a few tips:

• Brush your teeth twice daily.
• Floss daily- Flossing helps remove plaque and food particles between your teeth, which your toothbrush cannot reach.
• Clean your tongue—A tongue scraper can gently clean the tongue, helping to remove bacteria. This is a common practice in Ayurveda, where it is believed to support detoxification and overall health.
• Quit smoking
• Visit your dentist regularly
• Sugar and acidic foods will contribute to tooth decay and erosion

A word on mouthwashes

Research has found OTC mouthwashes may cause dysbiosis of the oral microbiome. Most studies on clinical effectiveness have been performed on chlorhexidine, which, while clinically effective, may also reduce the diversity of oral bacteria. Less is known about other mouthwashes on the market, so evidence is challenging to obtain.

Another big topic!

Mouthwash Effects on the Oral Microbiome: Are They Good, Bad, or Balanced? (sciencedirectassets.com)

I hope you found this article of use.

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