Inflammation and the Immune System

By Linda Rath | June 8, 2022

If the experts are right, a lot of people are in a state of chronic inflammation.

This is different from acute inflammation, which causes pain and swelling when you twist an ankle or have a bad sinus infection. With acute inflammation, your immune system is doing exactly what it’s supposed to: release a torrent of chemicals to help heal injuries, fight infections and mop up cellular debris.

In theory, your immune system also knows when to turn off the tap, slowing the torrent to a trickle as you get better. This may not always happen, however, because factors such as aging, obesity and a typical American diet change the way immune cells communicate with each other and with the microbes that regulate them. When the immune system doesn’t get the signal to shut down, it keeps pouring out white cells — the body’s first responders. That’s when acute inflammation becomes long-term, or chronic.

Inflammation-Related Diseases

Chronic inflammation may be responsible for around 80% or more of noncommunicable diseases, including:

• Inflammatory forms of arthritis, such as rheumatoid arthritis, psoriatic arthritis and gout
• Obesity
• Heart disease
• Type 1 and type 2 diabetes
• Inflammatory bowel disease
• Celiac disease
• Asthma
• Many types of cancer, including breast, colon, lung and prostate cancer
• Certain mental health disorders, including schizophrenia and depression
• Autism
• Alzheimer’s disease

Listen to Your Gut

If inflammation has such serious consequences for health, how does the immune system — which exists to protect you — become so confused?

Most of the factors that derail the immune system can be traced to the microbiome, the collection of trillions of mostly friendly bacteria, viruses, fungi and other microbes living inside you — mainly in the gut but also throughout your body. These microbes are your immune system’s first teachers, training it to attack foreign invaders but not your own cells. When something disturbs the microbiome in a major way, its signals to the immune system can go awry, leading to chronic inflammation.

These microbes play a big role in whether you’re sick or well and, because there’s two-way communication between the gut and brain, they also can affect your mood and behavior.

Growing Up Together

Communication (called crosstalk) between the microbiome and immune system starts when you’re born and lasts until death, though it may undergo some major changes along the way. Babies born vaginally get their first dose of microbes in the birth canal. Babies born via cesarean section are likely to have a less diverse microbiome, which may predispose them to a greater chance of childhood allergies, asthma and obesity.

Your immune system and microbiome grow up together. Bacteria in breastmilk feed the new microbiome, boost the immune and digestive systems and support a child’s developing brain. At the same time, the microbiome trains immune cells to know the difference between harmful organisms, like the coronavirus, and friendly ones.  It also helps build and maintain the barrier that separates your digestive tract from the rest of your body. This multi-layered barrier contains immune cells that help defend it against pathogens, which helps protect your health.

Throughout life, you may encounter dozens of things that alter or reshape the microbiome. Antibiotics, poor diet, pregnancy, infections, older age, stress, trauma, obesity, even racial, gender or socioeconomic discrimination — all can cause dramatic shifts in the microbiome, which are often at the root of chronic inflammation.

The Microbiome and Inflammation

There are several ways your microbiome might contribute to inflammation, but they usually start with a change causing an imbalance in the number and types of microbes, often called dysbiosis.

A healthy microbiome is finely balanced. It maintains diversity by not allowing any one species to dominate, fends off pathogens and regulates the immune system through constant crosstalk with immune cells. When this balance is disrupted, inflammatory microbes may take over, leading to an inflammatory immune response. In some cases, the intestinal barrier starts to break down. This allows proteins and other large molecules to escape into the bloodstream, triggering an immune response.

Can You Control Your Microbiome?

There’s little doubt that a dysregulated microbiome can lead to an out-of-control immune system and chronic inflammation. You may not be able to control everything that impacts your immune system, but you can control some players in the microbiome.

• Antibiotics. These can destroy the microbiome. Antibiotics can be life-saving but sometimes they’re taken needlessly for a minor infection or even the suspicion of one. If your doctor prescribes them, be sure they’re really needed and you understand why.
• Food. Let’s face it: Americans eat a lot of unhealthy foods in large quantities, including red meat, sugar, inflammatory fats, sodas and fast and highly processed foods, with plenty of preservatives and other chemicals mixed in that can unbalance the microbiome. On the other hand, many studies have shown that a Mediterranean-style diet, rich in vegetables, fruits, whole grains, olive oil and oily fish like salmon, can dramatically reduce inflammation in conditions ranging from heart disease to gout. Some studies have also found that the flavonoids in fruits and vegetables may help protect the intestinal barrier.
• Weight. Fat cells are pro-inflammatory, and excess weight is a key disrupter of the microbiome and intestinal barrier. Some research also links obesity-related inflammation to neurogenerative disorders like Alzheimer’s disease.
• Stress and trauma. Life stressors and trauma exact a cost not only on physical and mental health and well-being, but on the microbiome, leading to an uncontrolled inflammatory immune response.