Our wonderfully complex immune system consists of cells, molecules and tissues which work together to protect the body from “foreign invaders”. When it encounters one, the immune system releases an arsenal of chemicals and antibodies to find and wipe out these invaders, and then has the capacity to remember literally millions of these pathogens for a rapid response if ever encountered again.
There are several arms of the immune system to deal with invaders depending upon whether they are bacteria or virus or other intercellular pathogens (by up-regulation of the Th1 response and damping of the Th2 response) or whether they are large extracellular pathogens such as helminthes (resulting in an up-regulation of the Th2 response and a damping of the Th1). When communication breaks down between the different arms of the immune system, auto-immunity (attacking one’s own tissue) may occur.
As humans, and their immune systems, have evolved one foreign invader: helminth parasites, have also evolved and formulated several clever mechanisms to manipulate and evade the immune system. One of which is a dampening of the immune response (activating a Treg response).
One hypothesis (the hygiene hypothesis) given for the rise in auto-immunity in developed countries, may be that, due to impaired development of the immune regulatory system, at an early age, from the lack of intestinal flora and fauna has caused a shift of the immune system to a hyper-Th1 response.
Helminth Therapy to treat autoimmunity has been investigated with growing interest in the last 10 years. Several groups have demonstrated that helminthes can both protect and stop ongoing auto immune disease (see: http://dx.doi.org/10.1016/j.ijpara.2012.10.016).
In order for helminth therapy to be effectively developed the support of pharmaceutical companies is required. The paper reviewed in our Helminth 690 course: Tilp et al, International Journal for Parasitilogy 43 (2013) 319-325 (http://dx.doi.org/10.1016/j.ijpara.2012.12.003) suggested a number of reasons why this support may be stymied.
There is currently a very complicated picture immerging about Helminth Therapy: 1) not all helminth infections result in reduced autoimmunity’ 2) cohort studies performed in different labs have given different results’ 3) in many cases where there is reduced auto-immunity after helminth therapy auto-immunity still develops to some extent.
Several factors for why pharmaceutical companies are not investing in Helminth Therapy are the lack of reproducibility in current data; and the need for quality controlled clean helminth products; and the requirement to test Helminth Therapy for the relevant auto-immune disease with the correct timing; and marketing issue – making ingestion of parasites palatable to the public.
The Tilp et al., paper suggested several ways in which pharmaceutical participation could be enhanced. One of which was making helminth therapies for “orphan diseases” (diseases which are devastating but occur at low rates), for these diseases the extensive clinical trials and regulations are fast-tracked, thereby making it worth the time and money in developing them. Also, support could be enhanced by ensuring that the therapy is or can be patent protected. Other ways in which interest from the pharmaceutical companies could be enhanced would be for researcher to specifically address many of the outstanding questions such as the safety and side effects of Helminth Therapy.