Tumor necrosis factor is a protein found in the human body. Doctors link it with many inflammatory conditions, including forms of arthritis.

In a healthy person, tumor necrosis factor (TNF) helps the body to fight off infections. In people with autoimmune diseases, however, high levels of TNF in the blood can cause unnecessary inflammation, resulting in painful symptoms.

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TNF is involved with inflammatory conditions such as psoriatic arthritis, rheumatoid arthritis, ulcerative colitis, and Crohn’s disease.

TNF can also kill certain tumor cells. Researchers are looking into ways they can use TNF to treat certain types of cancer.

In this article, we look at how TNF can cause inflammation. Also, we cover symptoms of increased TNF, links with medical conditions, and ways to lower TNF in the body when it is part of inflammatory conditions.

Tumor necrosis factor and inflammation

man sitting on settee drinking coffee
TNF is a protein that helps fight infection.

TNF is a protein that plays a role in the natural healing process. When a person sustains an injury or experiences bacterial or viral infections, their body creates inflammation to protect the area and allow it to heal.

To create inflammation, TNF proteins begin to circulate in the blood. They arrive at the target area to trigger the inflammation process.

In healthy people, the body deactivates any excess TNF in the blood so it does not cause excess inflammation. When this process does not work properly, people can develop an autoimmune condition.

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Excess inflammation, even when the body is not damaged, characterize autoimmune conditions. Examples of these include rheumatoid and psoriatic arthritis.

Types of TNF

There is a family of TNF proteins, and each type plays a different role in the body.

According to Arthritis Research UK, in the late 1980s and early 1990s, Professor Ravinder Maini and Professor Marc Feldmann at the Kennedy Institute showed that excessive production of a particular type of TNF, called TNF alpha, drives the damaging inflammation present in rheumatoid arthritis.

TNF alpha does this by triggering the production of several immune system molecules, including interleukin-1 and interleukin-6. Both of these molecules are involved in a process that destroys cartilage and bone, driving even more inflammation and leading to the symptoms of many autoimmune diseases.

Symptoms of high TNF

In healthy people, high levels of TNF are nothing to worry about. The body is able to regulate its immune responses and avoid unnecessary inflammation.

For people with an autoimmune disease, however, high levels of TNF can lead to flare-ups of their condition.

Links with medical conditions

Researchers have linked many autoimmune conditions to high levels of TNF alpha in the blood. In such conditions, the protein leads to excess inflammation, which in turn leads to symptoms such as pain.

All of these conditions are chronic, long-term conditions, meaning they have no cure. Inflammatory conditions that doctors link with TNF include the following:

Rheumatoid arthritis

woman with pain in hand and wrist
Rheumatoid arthritis often affects the hands and wrists.

About 1.5 million people in the United States have rheumatoid arthritis and almost three times more women have the condition than men.

Inflammation that causes the tissues on the inside of the joints to thicken characterizes rheumatoid arthritis. It most commonly affects the joints of the hands, feet, wrists, elbows, knees, and ankles which can become stiff and swollen.

In women, it usually starts between 30 and 60 years of age, whereas it often occurs later in life for men.

Psoriatic arthritis

Around 30 percent of people who have the skin condition psoriasis will also develop psoriatic arthritis.

The symptoms include joint pain and stiffness. People often also experience rashes on the skin and changes in the nails. The condition can cause fatigue, problems with the eyes, and swelling and tenderness in the fingers and feet.

Juvenile arthritis

Juvenile arthritis, or pediatric rheumatic disease, is an umbrella term. People use it to describe the many autoimmune and inflammatory conditions that affect those under 16 years of age.

These include:

The different types of the condition share many common symptoms, such as pain, joint swelling, skin redness, and warmth. They can also impact on the eyes, skin, muscles, and gastrointestinal tract.

Inflammatory bowel disease

Inflammatory bowel disease (IBD) refers to a group of gastroenterological conditions. These include Crohn’s disease and ulcerative colitis, which together affect around 3 million adults in the U.S.

Characteristics of Crohn’s disease and ulcerative colitis are excess inflammation in the gut. This leads to symptoms including pain, fatigue, rectal bleeding, and diarrhea.

Ankylosing spondylitis

Ankylosing spondylitis is a type of arthritis that mainly affects the spine. It causes inflammation in the joints, or vertebrae, of the spine. This results in pain that can be severe.

Along with its effects on the spine, ankylosing spondylitis can also affect other areas of the body, causing widespread pain and stiffness. It most commonly affects the:

  • shoulders
  • pelvis
  • ribs
  • heels
  • the small joints in the hands
  • the small joints in the feet

Symptoms of ankylosing spondylitis tend to develop first when someone is between 17 and 45 years of age.

How to lower TNF levels

People with inflammatory health conditions can lower TNF levels in the body with a range of treatments, as we discuss below.

TNF inhibitors

person being given injection into thigh
A doctor may give TNF inhibitors by injection.

Doctors will often prescribe people living with an autoimmune condition drugs they call TNF inhibitors.

There are a number of these medicines, which doctors also refer to as anti-TNF therapies. People can only get them with a prescription. TNF inhibitors include:

Doctors can give TNF inhibitors through injections under the skin, usually at the thigh or abdomen, or as an infusion directly into a vein.

People take these medicines over a long time, and it will usually take around 3 months for them to start to notice a difference.

As with all medications, anti-TNF can cause side effects. These include pain or swelling at the injection site and an increased risk of infections, including tuberculosis and fungal infection.

Doctors will usually monitor people who are taking anti-TNF drugs for signs of side effects.

Curcumin

Some researchers have suggested that curcumin, a key compound in turmeric, can decrease the levels of TNF in the blood.

The authors of a review study published in 2013 looked at all of the available evidence linking curcumin to TNF and other inflammatory markers.

The researchers concluded that curcumin did appear to be able to suppress pathways that lead to inflammation. Most of the studies they included in the review, however, involved a petri dish in a laboratory rather than human subjects.

Consequently, researchers must do more studies before they can confirm the effectiveness of curcumin as a TNF blocker in humans.

Pomegranate

Some anecdotal sources suggest that pomegranate fruit extracts can help decrease TNF levels in people living with inflammatory diseases.

A study published in 2012, however, found no evidence of this.

Summary

TNF is a protein that contributes to inflammation. In healthy people, it is an essential part of the immune system, helping the body mount attacks against invading bacteria and viruses and heal damaged tissues.

In people with autoimmune diseases, excess levels of TNF in the blood can lead to unnecessary inflammation. This response can result in symptoms that are often painful.

Doctors prescribe long-term anti-TNF medications to treat many inflammatory conditions, including various forms of arthritis and IBD. These therapies work by blocking the activity of excess TNF in the blood.