Industrialized nations might be too clean. The “hygiene hypothesis” suggests that decreased exposure to microbes and certain worms in industrialized areas could lead to incompletely developed immune regulation that controls specific inflammatory responses. These uncontrolled inflammatory responses are the culprit in leading to autoimmune disorders such as type-1 diabetes, rheumatoid arthritis, Crohn’s disease, and lupus.
Developing countries have a high percentage of people infected with small parasitic worms called helminths that have likely helped human immune systems evolve a type-2 immune response over millions of years of evolution. People with autoimmune disorders tend to have an underdeveloped type-2 immune response.
Researchers at Rutgers University are studying the relationship between these parasites and the type-2 immune response. They found that by introducing helminths to mice for two weeks, the mouse immune system produced cytokines and gave the mice lasting protection from type-1 diabetes. This finding is supported by humans in developing nations where helminth infection is endemic but autoimmune disorders are very low. Additional research in this area will hopefully lead to a controlled way to apply the benefits seen with helminths to the immune system.