Old Friends Theory
An explanation for the Autoimmune Disease Epidemic
Autoimmune diseases arise from abnormal immune response against substances and tissues normally present in the body.
There are over 100 known autoimmune diseases affecting one in five Americans.
In recent decades, prevalence of these diseases have increased at an alarming rate.
- Celiac Disease
- Crohn’s Disease
- Multiple Sclerosis
- Type 1 Diabetes
The “Old Friends Theory” suggests that humans evolved with a range of microbes, creating a relationship of interdependency and symbiosis.
Over millennia, humans were under unremitting selection pressure as they came into constant contact with microbes and pathogens. For perspective, modern humans dispersed from Africa roughly two hundred thousand years ago whereas bacteria pre-date human existence by millions of years. While parasites are traditionally thought to be “bad”, recent discoveries reveal greater importance of micro-organisms in the ecology of the human body. Certain co-evolved parasites, or “old friends”, are not harmful, but possibly crucial to healthy human existence.
Intestinal microbes and helminths evolved to regulate the human immune system.
While the body typically declares war on foreign invaders, helminths have been demonstrated to down-regulate the immune system to keep themselves from being wiped out. The dampening effect on the immune system creates higher response threshold for all foreign bodies including pollen, foods, and other antigens. Helminths naturally reduce inflammation and promote diversity of gut flora – two factors that are a common thread across nearly all autoimmune disorders.
Industrialized countries have higher rates of autoimmune disorders than those of undeveloped countries.
Growing up without “old friends” may create an unbalanced immune system leading to autoimmune disorders.
The development of a child’s immune system is at its most pliable in the earliest years, months, and even seconds of a child’s life. First contact with bacteria and pathogens create long-lasting impressions for immunity; and maternal infection plays an important role in development of the fetus.
- Straubinger, K. et al. Maternal immune response to helminth infection during pregnancy determines offspring susceptibility to allergic airway inflammation Journal of Allergy and Clinical Immunology , Volume 134 , Issue 6 , 1271 – 1279.e10, 2014
- Neu, Josef, and Jona Rushing. “Cesarean Versus Vaginal Delivery: Long Term Infant Outcomes and the Hygiene Hypothesis.” Clinics in perinatology 38.2 (2011): 321–331. PMC. Web. 18 Feb. 2015.
- Cox, Laura M., Shingo Yamanishi, Jiho Sohn, Alexander V. Alekseyenko, Jacqueline M. Leung, Ilseung Cho, Sungheon G. Kim, Huilin Li, Zhan Gao, Douglas Mahana, Jorge G. Zárate Rodriguez, Arlin B. Rogers, Nicolas Robine, P’Ng Loke, and Martin J. Blaser. “Altering the Intestinal Microbiota during a Critical Developmental Window Has Lasting Metabolic Consequences.” Cell 158.4 (2014): 705-21.
Academic research accelerates in support of the Old Friends Theory.
- Lyte, Mark. Microbial Endocrinology: The Microbiota-gut-brain Axis in Health and Disease. New York, NY: Springer, 2014.
- Rook, G. A. W., C. A. Lowry, and C. L. Raison. “Microbial ‘Old Friends’, Immunoregulation and Stress Resilience.” Evolution, Medicine, and Public Health 2013.1 (2013): 46-64.
- Hays, Russell, Adrian Esterman, Paul Giacomin, Alex Loukas, Robyn McDermott. “Does Strongyloides stercoralis infection protect against type 2 diabetes in humans? Evidence from Australian Aboriginal adults” Diabetes Research and Clinical Practice, doi: 10.1016/j.diabres.2015.01.012
Helminthic therapy, the treatment of auto-immune disorders using various helminths, is being developed and tested.
- Trichuris Suis Ova (TSO) is an orally-administered suspension of microscopic eggs from whipworm species found in pigs. While human whipworm(Trichuris Trichiura) attaches to the intestine for up to five years, the lifespan of pig whipworm in humans is only about two weeks. TSO is being developed commercially with aims of getting FDA-approval for clinical use.
- Clinical Trials:
- NCT01413243 Multiple Sclerosis
- NCT01836939 Severe Plaque Psoriasis
- NCT01433471 Ulcerative Colitis
- NCT01040221 Autism Spectrum Disorder
- NCT01953354 Ulcerative Colitis
- NCT02011269 Plaque Psoriasis
- NCT01734941 Pediatric Autism Spectrum Disorder
- NCT02140112 Autism Spectrum Disorder
- NCT01948271 Chronic Plaque Psoriasis
- Coronado Biosciences, the US-based financing company, pulled support for the clinical trials, ceasing all development – read more here
- Clinical Trials:
- Necator Americanus is a species of soil-transmitted helminth(hookworm) that penetrates the skin and journeys to the small intestine with a lifespan from three to five years in humans. Hookworm was once widespread in the United States until 1909 when the Rockefeller Sanitary Commission (RSC) began a program to eradicate hookworm. Today, the CDC estimates 576-740 million people are infected with hookworm globally with a the majority having no symptoms.
- Clinical Trials:
- NCT01661933 Celiac Disease
- NCT01470521 Multiple Sclerosis, Relapsing-Remitting
- NCT02262403 Hookworm Immune Regulation Project
- NCT00469989 Effects of Therapeutic Hookworm Infection in Asthma
- NCT00232518 Effect of Therapeutic Hookworm Infection in Allergic Rhinoconjunctivitis
- NCT00671138 Evaluating Immunity and Gluten-sensitivity
- Clinical Trials: