Intestinal Barrier: Gateway to immune system

removing a tick from skinBacteria, viruses, fungi, man-made toxins, and natural toxins are everywhere. They are in food, air, and water. Bacteria and viruses can be transferred by specific vectors like ticks and mosquitos. There is no place to escape. Nevertheless, the human body is equipped to handle these ubiquitous influences because of the barriers to entry into the body.

The most obvious barrier is the skin. Seven layers of epithelial cells stacked and closely knit together by proteins called keratins. The lining of the intestinal tract has a barrier. The lungs have a barrier. And just in case something gets through these three gateways, there is a blood-brain barrier.

The gut barrier is one of the three functions of digestion. As an analogy, if you thrust your fist into a balloon, the outside skin becomes the inside skin. In between the inside skin and the outside skin is air. The air represents your body. Accordingly, when you ingest something it is technically not in your body until it crosses the barrier.

The gut barrier is composed of a thin lining of mucous over a single layer of epithelial cells, the same cells that comprise the skin. Between each cell is a zipper-like protein that is called the tight junction. When the tight junction is broken, the gut barrier is compromised. This condition is referred to as intestinal permeability or sometimes “leaky gut”.

It is estimated that seventy percent of the immune system is located in the gut. There is a constant, enormity of activity from destroying and eliminating bacteria, fungus, and viruses. Undigested proteins from foods are recognized as viral proteins and treated as such by the gut immune system. The gut environment is a fine balance of inflammation and repair. Sometimes the influences overwhelm the immune defenses or the immune system overreacts, creating a chronic inflammatory environment. The overburdened immune system cannot prevent damage to the intestinal lining, an important barrier to the body and vital organs. Once past the gut barrier, the body or somatic immune system reacts vigilantly to the same bacteria, viruses, fungi, man-made and natural toxins. Bear in mind that the immune system is finite so without the gut barrier the somatic immune system can be easily overwhelmed. When the immune system cannot keep up with the chronic invasion, symptoms begin to develop. A compromised gut barrier is the very beginning of many symptoms, syndromes, and diseases.


Immune System and Autoimmune Disease

Intestinal permeability is correlated with autoimmune diseases, headaches, insomnia, lyme disease, and psychological conditions including anxiety, depression, neurosis, and schizophrenia.

In its 2005 Report on Progress in Autoimmune Diseases Research the research committee stated “while many diseases (autoimmune) are rare, collectively they affect 14.0 to 23.5 million people in this country.” To put this into context, cancer affects about 12 million people and heart disease affects approximately 18 million people. Yet autoimmune diseases are more prevalent than cardiovascular diseases and cancer combined. In a 2011 study, the National Institute of Environmental Health Sciences estimates that “more than 32 million people in the United States have autoantibodies”. The 2005 report goes on to say “More than 80 human diseases are due at least in part to an inappropriate immune system response that results in damage to an individual’s organs, tissues, or cells. Autoimmune diseases can affect any part of the body, and have myriad clinical manifestations that can be difficult to diagnose. At the same time, autoimmune diseases share many features related to their onset and progression. In addition, overlapping genetic traits enhance susceptibility to many of the diseases, so that a patient may suffer from more than one autoimmune disorder, or multiple autoimmune diseases may occur in the same family.”

Some of the more common named autoimmune diseases are Psoriasis, Rheumatoid Arthritis, Hashimoto’s Thyroiditis, Hepatitis, Sjogren’s Syndrome, Lupus, and Multiple Sclerosis. At the core of these diseases is a hypervigilant immune system that attacks its own tissue because the tissue resembles a virus or other protein with which the immune system had an experience. This is called molecular mimicry and is an important understanding of the cause of autoimmune diseases. It is the undigested proteins, viruses, bacteria, fungus and other environmental influences that pass through the compromised gut barrier and are attacked by the somatic immune system. The somatic immune system is on guard against any cell that even looks like the trespasser, including one’s own tissue and cells.


Lyme Disease and Intestinal Permeability

In a condition of intestinal permeability the somatic immune system is overwhelmed and can barely keep up with the onslaught of influences, especially when it is confronted with the stealth bacteria Borrelia burgdorferi, the bacteria implicated with Lyme disease. Lyme disease is the symptom picture associated with an overwhelmed immune system combined with an unidentified autoimmune disease. Many of the psychological conditions, as well as insomnia, are part of chronic Lyme disease. Despite a multitude of physical and psychological symptoms, Lyme disease is the manifestation of leaky gut.

Once it is recognized, intestinal permeability can be repaired. First, remove the source of chronic inflammation. Then nourish the epithelial cells so they may replicate and develop new tight junctions. Once the gut barrier is restored, the somatic immune system will rebalance itself and hyperactivity will subside.


Progress in Autoimmune Disease Research, National Institutes of Health The Autoimmune Diseases Coordinating Committee, Report to Congress, March 2005.

Turner J. Intestinal mucosal barrier function in health and disease. Nature Reviews/Immunology 9: 799-809, 2009.

Fasano, A. Zonulin and Its Regulation of Intestinal Barrier Function: The Biological Door to Inflammation, Autoimmunity, and Cancer. Physiol Rev 91:151-175, 2011.

Fasano, A. Mechanisms of Disease: the role of intestinal barrier function in the pathogenesis of gastrointestinal autoimmune diseases. Gastroenterology & Hepatology 2; 416-422, 2005.

Oldstone, M. Molecular mimicry and immune-mediated disease. FASEB J. 12, 1255-1265. 1998.

Satoh M et al. Prevalence and sociodemographic correlates of antinuclear antibodies in the United States. Arthritis and Rheumatism. doi:10.1002/art.34380


Family and Environmental Medicine help patients with Natural and Holistic Treatments for a healthy immune system. Dr Gary Gruber provides private appointments for patients from around the country who seek health and healing with Complementary and Alternative Medicine. The majority of patients are from the local area including Greenwich CT, Stamford CT, Darien CT, Norwalk CT, New Canaan CT, Wilton CT, Westchester County, NY, NYC, and Northern NJ.