Sunday, 28 September 2014

Hookworms and the Treatment of Celiac Disease

A hookworm attached to the intestinal lining
Public domain photo from the CDC
Researchers in Australia have just reported some strange but very interesting results obtained from a clinical trial. The scientists found that a hookworm infection helped a small group of people with celiac disease. Hookworms are parasites that live in the small intestine and are normally harmful. Celiac disease is a serious disorder in which the lining of the small intestine is damaged. The link between the worms and the disease is intriguing and unexpected.

In people with celiac disease, the presence of a protein complex called gluten causes inflammation in the small intestine and the destruction of villi. The villi are tiny folds on the intestinal lining which absorb digested food. Without villi, the absorption of nutrients is greatly reduced. Gluten is present in several grains, including wheat, and is an additive to foods, medications and other products. It's a useful substance because it acts as a binder.

The consequences of untreated celiac disease can be serious. The villi can regrow, but this will only happen if the patient completely avoids the ingestion of gluten. When someone with celiac disease ingests gluten they experience symptoms such as cramps, vomiting and diarrhea as well as increased inflammation and villi damage in their gut.

Most spaghett is made from wheat, which contains gluten.
Photo by yamado taro at publicdomainpictures.net
Twelve brave people with celiac disease volunteered to eat gluten in a research study at James Cook University in Australia. The researchers infected each of the patients with twenty larvae of a hookworm (Necator americanus) at the start of a year long experiment. The patients were then given increasing amounts of gluten to eat. The once-a-day servings started with a single piece of spaghetti less than one inch long and ended with seventy-five pieces of spaghetti, or one bowl. A bowl of spaghetti would normally trigger horrible symptoms in someone with celiac disease, but the patients who completed the study experienced no unpleasant effects.

The researchers obtained samples of tissue from the intestinal lining of the test subjects before, during and at the end of the trial and found an interesting change in the patients' T cells. T cells are a type of white blood cell and are part of the immune system. This system protects us from invaders, such as bacteria, viruses and - in some people - gluten. The scientists found that the T cell population in the intestine of the patients changed from being pro-inflammatory to being anti-inflammatory during the trial.

Tissue obtained from a biopsy of the small intestine in a
patient with celiac disease; the villi at the tips of the folds
are flattened
 Photo by Samir, CC BY-SA 3.0 License
The researchers say that at the end of the trial they offered the test subjects medications to destroy their hookworms, but all of the subjects refused the offer. They were told to stop eating gluten even though their hookworm population had helped them. Celiac disease is too serious to experiment with unless a patient is being closely monitored.

How were the hookworms helping the patients? The researchers don't know for certain, but they think that the worms were secreting anti-inflammatory proteins so that they wouldn't be damaged by the body. These proteins are believed to have protected the intestinal lining.

The results of the study are exciting. Only eight people completed the year long trial, however. The investigation really needs to be performed with more people. In addition, one point that is missing from the university's news release is any mention of whether the villi of the test subjects recovered. Still, the discovery is important and offers great hope for the future.